Add option to run java tests with run.py
Java API: fix build warning on OS X

Common part of all source files is extracted to special header
Java tests: print summary for tests run
Quiet output of cv::error in Java tests

Introduced new Java API
void org.opencv.core.Core.setErrorVerbosity(boolean verbose)
used to suppress output to stderr from OpenCV's asserts
Enable Java bindings on all platforms by default