Add changelog.

Signed-off-by: crynobone <crynobone@gmail.com>
Merge branch '2.0' into 2.1
Add v2.1.x changelog.

Signed-off-by: crynobone <crynobone@gmail.com>
Update README.

Signed-off-by: crynobone <crynobone@gmail.com>
Update changelog for v2.1.2 release.

Signed-off-by: crynobone <crynobone@gmail.com>