Add a search all indexers to api

if indexer is omitted is will search on both indexers unless its a tvdbid or tvrageid in the url.
cmd=sb.searchindexer&name=solsidan
cmd=sb.searchindexer&tvrageid=2930
cmd=sb.searchindexer&tvdbid=70327
cmd=sb.searchindexer&indexerid=2930&indexer=2