Make it easier to build the docs

Following the instructions will install the latest version of Jekyll,
but the Brooklyn website is not compatible with this. Provide a
`Gemfile` and `Gemfile.lock` with known good versions of Jekyll and
other dependencies, and update the instructions to use `bundler`.
Change from @andreaturli for Docker port forwarding
Merge pull request #1420 from grkvlt/fix/docker

Change from @andreaturli for Docker port forwarding
Merge pull request #1394 from richardcloudsoft/doc-build-fixes

Make it easier to build the docs
New config keys for optional custom CHECK_RUNNING and STOP commands.
Added initial SaltStack classes, based on existing Chef code
Updated salt-master and salt-minion install tasks
Adding salt support (and postgres impl)
Added SaltStackMaster entity

- Master entity framework is in place
- Tasks to install master and minion available
- Config templates for /etc/salt files for master and minion
- SaltConfig with some configuration keys for minions
Modified SaltStack to use masterless minion configuration initially
Add masterless mode configuration key for Salt
Tidy up code
Remove Chef references in PostgreSqlSaltLiveTest
Fix formula directory listing and other configuration issues with templates
Remove annotation as per @aledsage review comment
WIP
Removed unwanted Nginx for Salt
Move to sandbox
test #1 to fix rebind in non-AWS clouds
Fix build errors caused by Brooklyn updates