Various upload changes

* 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
Version bump to 0.5.14-alpha

* added some documentation (JavaDoc)
* CTags are not cached in LocalCollection anymore
* added CTag test for LocalCalendar
Allow only one anniversary to comply with VCard 4 (fixes #277)
Don't crash when Calendar Provider is not available at account creation
(fixes #276)
Handle HTTP redirections (fixes #83)
Add support for well-known URIs (RFC 5785) - closes #148
Version bump to 0.6 (drop -alpha suffix)
Handle redirections to relative URLs correctly (see #282) + tests; minor GUI change
Add first simple VTODO support
need to implement improved ContentProvider on Mirakel-side
Lint-fixes
Enable gradle build
Update gitignore
Add proguard to release-build
Improve proguard
Update gradle
Update gradle
Merge