Resolve a merge conflict

When ast_channel_cached_blob_create was merged,
ast_channel_blob_create_from_cache was partially removed in an
unresolved merge conflict. This restores ast_channel_blob_create_from_cache
and refactors usage of ast_channel_cached_blob_create (requires an
ast_channel) to use ast_channel_blob_create_from_cache (requires a
channel uniqueid) instead.


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@389974 f38db490-d61c-443f-a65b-d21fe96a405b