Add auto-generated solum.conf.sample

Add a script that automatically generates solum.conf.sample.  Include
the initial config sample.  This should be updated every time an option
is added, changed, or removed.  We can add an automatic check for this
at some point, as well.

Change-Id: Iace8c4a3c5b63f5f3808e5bb725b23086bf3d840
Merge "Add auto-generated solum.conf.sample"