Eliminate intermediate build target "opencv_java_api"
Hardly refactored CMake script for Java wrappers
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
Merge pull request #315 from taka-no-me:java_on