This commit includes the major changes between DAVdroid and EteSync. It
adjusts the app to use the EteSync protocol and server. It includes some
ugliness still, and it's a squash of many ugly snapshot commits while
hacking on the initial DAVdroid code.
History should be "clean" from this point onwards.
* allow ProGuard optimization to remove non-relevant bytecode from flavors
* check flavors with direct comparison instead of .equals() to allwo optimizations
* store cookies per HttpClient, and not per DAVdroid instance (allows multiple sessions for parallel syncs)
* fetch translations from Transifex
* upgrade to okhttp 3.3 to reduce HTTP/2 incompatibilties
* vcard4android: enable RFC 6868 support in ez-vcard
* minor improvements and bug fixes
* new translations from Transifex
* version bump to 1.0.9
* 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