Added a WIP of GitLab on Debian 7 deployment.
Added `bunch` to provide `dict`-like Python class.

This will replace a custom-written class to handle the same thing, which allows
both `a.b` and `a['b']` for references to fields in JSON-like objects.
Replaced custom `Dict` class with `Bunch`.

Also disambiguated the difference between `$PYTHONPATH` (search path for Python
files, which is a list of paths like `$PATH`) from the source path (where our
Cloud Launcher core source code is found) which is now `$SOURCE_PATH`, and is
now just one of the directories in `$PYTHONPATH`.
Add a blank line before first top-level class.
Remove commented out setting for `$PYTHONPATH`.
Switch from `execfile()` to `imp.load_source()`.

This enables us to have files which have `import` statements, but because it
disallows us to inject custom imports before loading, it comes at the cost of
forcing users to add `import gce` or `from gce import *` explicitly to the top
of their files. As a side-effect, this enables a multi-cloud strategy.
Update GitLab with explicit GCE imports.
Update HDP with explicit GCE imports.
Deployment of RabbitMQ on Debian 7.
Added README for RabbitMQ.