Add a search all indexers to api

This pr will add a new "endpoint" in the api where you can search both tvrage and tvdb for a show
I need this in order to add sickrage awesome features to htpc manager.

Search both indexers
/api/1234/?cmd=sb.searchindexer&name=solsidan 
Search for a name on only one indexer (tvdb)
/api/1234/?cmd=sb.searchindexer&name=solsidan&indexer=1
Search for showid on a indexer
/api/1234/?cmd=sb.searchindexer&tvrageid=1337