* fix lint warnings
* line-break too long messages of network trace logs
* DebugInfoActivity "send": attach log file instead if sending it as plain text
* revert to ez-vcard 0.9.6 because of https://github.com/mangstadt/ez-vcard/issues/33
* German translations
* use VERSION_CODE and buildTime from BuildConfig
* new HTTP User-Agent, VCard PRODID values
* contact sync: store CTag in SyncState
* sync logic: upload contacts, check CTag, multiget