Merge pull request #230 from sudorandom/master

Removes un-needed mask[] from docs
Update requirements.txt
Merge pull request #231 from briancline/requirements

Update requirements.txt
Fixes two misc VM-related bugs

CLI: Fixes an issue with `sl cci detail` where a CCI might not have an operating system.
API: When creating a CCI with the manager, if you send in disks as an empty
	 list, [], an IndexError occurs. This fix makes that work better.