Switching to PersistableBundle in carrier config API.

Part of this API involves persisting config bundles to avoid binding to
apps at critical moments (like boot). Regular bundles should not be
written to disk because they support object types that can lose their
meaning while the data is at rest.

In order to use PersistableBundle, we must either start with one or
filter unwanted types out of Bundle objects. Since the carrier config
API has no use for unsupported types, we chose to use PersistableBundle
everywhere.

Bug: 20268926
Change-Id: I17989ce840014c2a0ed3679c1bca5a8498082c7f