updated __doc__ strs and plays nice with flake8

* Show.get method now also returns the date of last_viewed and recently added
values.
* some doc strings were updated.
caching now pops arguments out of kwargs
methods now raise AttributeError if year is not supplied
re-worked the search command

* uni starts soon and i don't have as much time to play with ftrack. this commit
has some basic search functionalities worked in. it does not render any html
files but it does display basic information at the end of each search. i'll
spend some time to add rendering and fixing the search command's code base a
little more when i have the time.