Building off of jgoguen's docker work added env files and custom domain support

[wetnun]

I forked off of @jgoguen with his docker and branch support and added:

• moved from csv to dump file because of silly table name in db
• fixed bug with custom domains not working on agents because of missing group attribution
• use env.sh file to override most config options (my main node and agents use different structures) so no editing of git file required
• removed hard tabs (personal preference since all of my different shells tend to make things jump around but spaces are consistent)

The move to .dump from csv files also allows you to change one variable (I forgot to make it an override, should have done that) and just copy additional tables as needed. I have some domains I need to allow and I noticed that on my agents the domains showed up without group assignments (like 'default') so they never got applied and gravity always blocked things.

Potential improvements:

• put $branch into env.sh to avoid needing to pass it in
• setup DB_TABLES to allow overrides with env.sh

[wetnun]

Added my own suggestions for improvements. I'll eventually want to sync clients and groups in my case. So override of those additional tables will be required.

[stevejenkins]

Thanks. Merged.