* remove debug settings activity; logging can now be enabled via adb setprop, since that's the default way of enabling verbose logs in HttpClient's Android flavour and adb is required for viewing the logs anway
* update i18n accordingly
* new icons with 3D effect as required in Android Iconography Guide
* target SDK version updated to 20
* replaced UI directions left/right by start/end for RTL support
* Show "unnamed calendar"/"unnamed address book" instead of "null" in "Select collections" fragment
* "Add account" button now directly adds DAVdroid account
* .svgz for "How DAVdroid interacts with other components" added to doc
* fix minor translation issue that caused DAVdroid to crash when showing an I/O error
* don't select TLS ciphers for Android 5.0+ (it has more secure default settings); closes#344
* a few fixes for SRV service detection
* localization strings cleanup
* new policy for localization: translators are only mentioned on their own translation from now on
* fix issue when first upload fails (fixes#233)
* show debug settings menu item in main activity
* update ETag in local database when a PUT request returns an updated ETag, meaning that
locally created/updated records won't be downloaded from the server immediately after the upload
* force debugging options for resource detection (because there's no way to turn them on until there's an account)
* provide "report issue" button in debug settings
* provide CONTRIBUTING.md, including instructions on how to report issues
* increase socket timeout from 20 to 45 seconds (hopefully fixes#237)
* previous commit: increase total simultaneous connections to 3 (2 per host)
* preference screen for debug settings
* allow to disable HTTP compression
* verbose network logging only when activated
* single HttpClient for all threads (before: single HttpClient per adapter)
* bump version to 0.5.13-alpha
* relevant RFCs go into the doc/ directory for reference purposes
* read-only calendar collections are set as read-only in Android
* HTTP exception refactoring to mark 4xx HTTP errors as hard sync errors (numAuthExcetions/numParseExceptions) for Android sync manager
* query current-user-privilege-set for resources, detect read-only resources
* show read-only resources as read-only in SelectCollectionsFragment
* minor refactoring (DavProp.*)
