Add a CCF setting and provision subscribers with it
Merge pull request #167 from Metaswitch/sto851

[Reviewer: AMC] Add a CCF setting and provision subscribers with it
Don't push IRSs to homestead_cache unless they contain a SIP URI
Merge pull request #171 from Metaswitch/police_irs

Reviewer Ellie: Don't push IRSs to homestead_cache unless they contain a SIP URI
Change Metaswitch submodule refs to ClearwaterCore