rename isAttributesValid() to areAttributesValid()
add Browser::isTablet() helper
serve single file media directly regardless of the singleFilePlaylist
setting when a mobile device is used (including tablets). Fixes #124.
factor out some stuff from Media to a separate Base class
map seasons to a dedicated Season class
don't render a TV show's cast on mobile devices
don't limit the TV show title to just half the available width

This is a copy-paste error from the movie details page where we
show the stream details to the right of the title/year
pass the whole Season object to the SeasonAccordion items

Also moved the widget so we can use views later
resize placeholder images too, this way we don't have to worry about
them appearing bigger than the rest of the images
add a new thumbnail size (very small)
add a class for representing season thumbnails
render season art, and number of episodes in the season list

Fixes #122, fixes #123
hide everything except the season number when a season is expanded
add method for fetching details about a single season
render the season artwork, season title and number of episodes in the
episode list too
update the minified stylesheet