Move configuration to YAML.

[cburschka]

Much cleaner syntax. Compile to json on build I guess? npm is bound to have a package for it, and we already depend on Babel.

[cburschka]

This is really just one step on the lengthy road to fix the build process.

The basic structure of the change is this:

• Convert config.tpl.js to config/default.yml
• setup.py no longer builds config.js, but instead loads the contents of config/default.yml and dumps them to JSON inside a special <script> element in index.html.
• The initializing code deserializes that JSON and places it in the config global variable.

[cburschka]

Additionally, moving from the relatively simple .config.vars to a YAML-based installation profile means the variables are no longer easily accessible to the Makefile.

This necessitates moving the install logic from the Makefile to a Python script install.py and calling that.