Allow SourceQuery to have either Text or [SourceTag]

Allows for Sieste to have key/value pair searching.

Should be backwards compatible. May not be used elsewhere, but included since SourceQuery uses other Chevalier Types.
change SourceQuery to accept only a list of SourceTags
minor version update - exposed type changed
Add travis file
Merge branch 'eitherText' of github.com:anchor/chevalier-common into eitherText
Merge pull request #7 from anchor/eitherText

Allow SourceQuery to have either Text or [SourceTag]