Make h5serv installable with pip and importable in other Python code

[telamonian]

Fixes #102, fixes #122, and fixes #123

Here's my use case for h5serv: I'm writing an HDF5 file viewer plugin for another Python program, and I want to use h5serv as a dependency. Basically, h5serv will be used to handle all of the low-level interactions between the program and a user's HDF5 files. Two things need to happen in order to make this possible:

1. There needs to be a (very) easy way for my end-users to install h5serv (ie pip install h5serv)
2. I need to be able to import components of h5serv into my own Python code (ie from h5serv import app), and there needs to be a way to use those components to start/stop an HDF5 server without actually having to spawn a new process.

The code in this PR aims to fix all of the things preventing 1. and 2. from happening.

[telamonian]

There's still a bunch of issues to fix that relate to conflicts between how this project's files/paths are structured, and the way in which setup.py and Python's setuptools "want" those files/paths to be structured.

For example, right now if I try to run the program using the h5serv command (the one that's set up by the newly fixed entry_points in setup.py), I get an error like:

FileNotFoundError: [Errno 2] No such file or directory: '/usr/local/log/h5serv.log'

This is because the h5serv command is installed as a script at /usr/local/h5serv and h5serv defaults to saving the log file at a position relative to that script.

[jreadey]

This makes sense. When I original setup the project I didn't think it was important to have a setup install script.

Do you plan to update the PR for the other issues?

Also the change breaks the travis tests. e.g.: https://travis-ci.org/HDFGroup/h5serv/jobs/437807772.

The travis script just needs to use the new name for invoking the server.

[telamonian]

Do you plan to update the PR for the other issues?

Working on it right now!

Aside from the Travis setup, some import statements in the tests are also broken by the changes, so I'll fix those too.

There's a bunch of tricky little problems relating to config and how it's handled. Here's how I'm thinking to resolve the issues:

• The current default behavior will be preserved when h5serv is invoked via python app.py
• When h5serv is invoked via a script or the h5serv command, the current working directory will be used as the default data dir, log dir, etc

[telamonian]

I took a crack at fixing the remaining issues. At least some tests pass now. The remaining problems all have to do with how the tests... ah... "creatively leverage" the quirks of the Python import system to override h5serv.config with their own local config module. I know how to fix it, but I'll probably have to make a couple of significant changes to how config works (at least internally).

[jreadey]

Looks like the Travis tests are passing, that's a good sign. Are there remaining known problems with the PR?

[telamonian]

Just needed some updates to the docs. The PR is now finished. Some notes:

• setup.py is totally fixed up, so as soon as you pull the changes and upload them to PyPI people should be able to install using pip install h5serv.
• After installing with pip, you can now run h5serv anywhere on a system using the h5serv command.
• Two user-visible changes you should be aware of:
  1. h5serv can now be run by cding to the root dir of the repo and then running python h5serv. This was done by fixing up h5serv/__main__.py, and replaces python h5serv/app.py (which is no longer executable).
     • This was done so that the same set of default paths could be used regardless of how h5serv is invoked.
  2. I got rid of the log directory, and by default logs are now saved directly to the working directory.
     • This was done to prevent the FileNotFoundError I described above.
     • In the future, you may want to add some more information about the expected file structure (/data, /static, etc) to the program's startup message, and/or optionally set up missing directories automatically.
• I updated the docs to reflect the above changes.

Let me know if you have any revisions @jreadey, or if the PR looks good to go!

[jreadey]

I tried the PR with the h5pyd test suite, and everything worked fine. Merging into develop. Thanks for the contribution!