Implement SwipeRefreshLayout

Forced sync is now possible by swiping down like e. g. in the G+ or
GMail-App.
Only enable swipe refresh for own list
Don't try to sync if there is no connection
Use synctask() for forced sync

forcesync() has done the same, so it was implemented twice (thx @ratan12
for pointing at it).
Fix notifications for synctask()

Only disable notification for swipe refresh.
Don't use holo colors from android resources

They are available for API 14+ only
Show loading indicator if forced update and clear=true
Merge pull request #180 from d-sko/swipe_refresh

Implement SwipeRefreshLayout
Fix results from previous search are shown (Search)
Merge pull request #187 from ratan12/Fix_search

Fix results from previous search are shown (Search)
Unify Anime/MangaNetworkTask

They are doing the same, so they can be easily unified. This makes less
and cleaner code.
Also changed GET and GETDETAILS tasks to return Anime/Manga objects
instead of ArrayLists with only one element (now possible as the task's
return type is Object since #176).
Implement NetworkTask cancelling

Don't continue loading data if the user selects an other list. This
prevents unnecessary loading of useless data and fixes #190.

Exception are FORCESYNC-tasks, there is no reason to interrupt them.
Instead let them finish but don't display results (thats why there is
the new "cancelled" parameter in the callback function).

Cancellation code is a little more complex as it could be because of our
low minimum API level. It can be simplified as soon as we drop < API 11.
Only display network error info if it is actually a network error