Fix NOT_RESTRICTED network capability and enforce it.

With this change:
1. NOT_RESTRICTED should be removed from NetworkRequests that bring up
   special restricted carrier networks (e.g. IMS, FOTA).
2. NetworkRequests without NOT_RESTRICTED require CONNECTIVITY_INTERNAL
   permission to register
3. Binding sockets to networks without NOT_RESTRICTED requires
   CONNECTIVITY_INTERNAL permission

Bug:21637535
Change-Id: I5991d39facaa6b690e969fe15dcbeec52e918321