Update the example, library, readme and removed SVN files

 - Upgraded library to better support 'force redownload' (Thanks to
Emanuel Andrada)
 - On 'low memory warning' instead of releasing all the images on the
RAM cache it will just wipe the last half of the images (images are
orderer by last acces time dec)
 - The library is now more thread safe (I won't say 100%)
 - The README was updated.
 - Removed all the SVN files/folder