VKSdk class improved, double checked locking singleton for thread safety calls to VKSdk.initialize(), cleaned code style
Improved TestApp's LoginActivity code
Improved TestApp's ApiCallActivity code
Improved TestApp's TestActivity code
Merge with #17. Improvement #18
#20
New models system. User can use parsers to specify rule for processing response
New models system. Merged from server. Clean up
Update version