Re-enable TLSv1.1/1.2 support

Was disabled in 3fd7470d.

Issue 6238.

Related Android change for API 20:
https://android.googlesource.com/platform/external/conscrypt/+/1f63d2c22326b989105366d2907a83b848dcd29e%5E!/
Update changelog for 4.905
Bumped manifest to 4.905
Add Play Store feature graphic assets
Move LocalStore to new subpackage to prepare decomposition of nested
classes.
Extracting local attachment classes from LocalStore to reduce file size.
More nested classes extracted from LocalStore.
Extracted LocalFolder and LocalMessage definition from LocalStore
Extracting Database Setup Schema definition form LocalStore.
Some minor code cleanings and logging for LockableDatabase
Use android-sdk-manager to fetch Android SDK dependencies
Update HoloColorPicker to use build tools 20.0.0
Add support for disabling pre-dexing
Use checkstyle to monitor code quality
Remove unused strings
Remove unused 'check mark' color chip
Fix code style
Merge pull request #3 from frommeyerc/merge-upstream

Extract inner classes from LocalStore
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/com/fsck/k9/mail/transport/SmtpTransport.java
Added testcases for parsing and removed unused methods for parsing