Merge pull request #29 from htgoebel/master

Fix installation guide: correct usage of make + PREFIX.
Merge pull request #30 from htgoebel/master

Add example for how to  update all managed machines.
Specify more explicit APT upgrade command
Updates in list of default service ports
Use correct target name
Merge pull request #31 from drybjed/small-fixes

Small fixes
Fix a typo
Merge pull request #32 from drybjed/typofix

Fix a typo
Remove all non local images to try fixing buiild
Remove requirements.txt to try fixing build
Add documentation for debops.salt
Fix the wrong Travis badge URLs
Merge pull request #1 from drybjed/add-salt

Add documentation for debops.salt, fix Travis badge
Install sphinx directly, not by requirements.txt
Merge pull request #2 from drybjed/fix-travis

Install sphinx directly, not by requirements.txt
Add link to Mailing list.