* detect CardDAV VCard version support using supported-address-data + test
* account setting for supported VCard version
* don't ask for calendar details when querying CardDAV collections
* don't ask for address book details when querying CalDAV collections
* ez-vcard update to 0.9.5 (fixes#268), adapted exception handling
* refactoring: unnecessary DavProp prefixes removed
* 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