Create a default 'info' key in the ContentDB
Tests updated to expect an 'info' field in ContentDB
raise PyslidException instead of returning nothing
raise PyslidException on errors
features.has should return a bool except for unexpected exceptions
Revert "Removed all references to PyslidException for now"

This reverts commit a6c2bfadd960ad3cdc51c65775b33e88e17280ad.