added pip packages: pytest, pytest-cov, coveralls

[kaylanb]

@tskisner ,

I added some unit tests using pytest and its plugin for coveralls to the imaging code base. The docs for these recommend pip installing so I added them to rules/pip_pkgs.sh

I tested the three-line change by successfully building and installing conda with "cori-gcc-py27".

Let me know! -Kaylan

[kaylanb]

Just found an issue. pip pytest py-cov converalls crashes the docker build with:

package plan for installation in environment /usr:

The following NEW packages will be INSTALLED:

    configparser:      3.5.0-py27_intel_3  intel [intel]
    entrypoints:       0.2.2-py27_intel_2  intel [intel]
    get_terminal_size: 1.0.0-py27_intel_5  intel [intel]
    ipykernel:         4.5.0-py27_intel_9  intel [intel]
...
Removing intermediate container 0782d7965def
Step 19/63 : RUN pip install --no-binary :all:     speclite     hpsspy     photutils     https://github.com/esheldon/fitsio/archive/v0.9.12rc1.zip     pytest     pytest-cov     coveralls
 ---> Running in ae93bd03922f
Collecting https://github.com/esheldon/fitsio/archive/v0.9.12rc1.zip
  Downloading https://github.com/esheldon/fitsio/archive/v0.9.12rc1.zip
    Complete output from command python setup.py egg_info:

    ----------------------------------------
Command "python setup.py egg_info" failed with error code -4 in /tmp/pip-xI0QP0-build/
The command '/bin/bash -c pip install --no-binary :all:     speclite     hpsspy     photutils     https://github.com/esheldon/fitsio/archive/v0.9.12rc1.zip     pytest     pytest-cov     coveralls' returned a non-zero code: 1

[tskisner]

This seems like a harmless change (adding a few packages to the list to be pip-installed). Did you figure out why this addition failed?

[weaverba137]

pytest & pytest-cov are conda packages, so they should be installed that way. coveralls is still only pip, I think.

[tskisner]

Ok, thanks @weaverba137 . I'll add them to the conda list and verify that it works.

[tskisner]

I added this separately in 6526ce7c5c47c241cc7668833f3e1117e8712721. Closing pull request now since it is no longer needed.