extraxt a search method to the api

I have build a simple webapplication based on this cool api (https://github.com/someone561/tvcal, https://tvdb-ical.appspot.com/) 
For this I need the search Result in a json webservice. I make a ugly hack (https://github.com/someone561/tvcal/blob/f2c3e9bf9e61dc5a3cdfea402a56692c872150fa/tvcal.py#L41) to this with the current api.

Adding a search method makes this a hole bit smarter.

The new search method is a extract of the _getSeries method.