Fixed #98 possible NPE

NPE was possible when constructing user-friendly exception message for a different problem. This change does not fix any underlying, environmental/classloading issues the user has. At least Mockito shows the right message.
Fixed #101 removed non-existing version from docs
Tuned the bintray plugin settings

Added vcs tag information, the default name of the vcs tag listed in bintray was missing 'v' before the version. Removed some commented out codes.