Switched from home grown image tool to Picasso

Moved from the home-grown image downloading and caching code to
Square's Picasso library (issue #56). Now we have the advantage of
stuff like memory caching and lots of little extras if we should need
them.

We still may want to set up some method to prune our image cache when
the user logs out.
Add Placeholder and Error Images

Make some simple placeholder and error image files for Picasso to use.
This prevents a previous cover from "flashing" when scrolling down. It
also makes for a nice placeholder as the application downloads the
images.

Additionally, include the source files that created the placeholder.
Merge pull request #69 from cyrieu/working

NavDrawer + Most Popular and Top Rated Anime lists
Cleanup gitmodules

Was an excess misspelled one. Removed it.
Auto-sync & bug fix

Added auto-sync to Atarashii
fixed some bugs at the first time login screen.
(i am still editing and submitting strings & settings)
get pref...
Add auto-sync to settings menu & cleanup
add auto-sync strings & cleanup
Update AUTHORS
added SherlockNavigationDrawer to readme
Merge pull request #1 from ratan12/patch-1

Auto-sync & bug fix!
Update Home.java
Fix bug when you are returning from top rated / popular.
Cleanup!
added only sync on wifi option (home.java)
added get wifi checkbox status (PrefManager.java)
added strings for wifi checkbox status (strings.xml)
added settings for only Wi-Fi (settings.xml)
Cleanup & returning from top/popular.
Cleanup.