Fixing girder packaging for pip install

Girder can now be installed using _pip install girder_. Only the API works at
this time. The next step is to get the static content working.
Adding documentation to cover pip case.

Also added some entries about config file precedent and log file location.
Implementing the documented config precedence.
Removing dev_endpoints.

This minor convenience is not worth the major inconveniences extra
imports cause with packaging, maintenance, etc.
Fixing missing / in config loader.
Fixing style.
Fixing pip-installed girder so one-page-app is served.
Small style fix in plugin_utilities.
Adding a plugin directory configuration for packaging.
Adding configurable logging.
Using better log config code.
Properly include plugins and remove cruft from the source distribution
Moved Sphinx to requirements-dev.txt
Added package task to grunt
Fixing merge conflict
Fixing test failures
Fixing paths for pip installed server
Removing plugins from main python package
Added a girder-install helper script
Packaging plugins and installing requirements