Added classes for accessing gpodder.net service

Directory + Subscription upload/download
Added ImageDiskCache
Improved AddFeedActivity layout, added gpodder.net toplist fragment
Added search, taglist, pocdasttaglist etc.
Set user agent header when making http requests
Added subscribe button to online feed view
Images in podcast directory should now be displayed correctly
Visual improvements when loading images
Added GpodnetPreferences
Implemented authentication process
Added subscription syncing
Added dialog to change password
Added suggestions list

Turned off at the moment
Upload changes instead of whole subscription list
Sync improvements
Improved layout of login GUI
Added missing up-navigation buttons
Always set ImageView tag when loading image
Merge branch 'gpoddernet' into develop

Conflicts:
	AndroidManifest.xml
	res/values/arrays.xml
	res/values/strings.xml
	res/xml/preferences.xml
	src/de/danoeh/antennapod/activity/PreferenceActivity.java