2016.04

• Add COMMON_OSX_TARGET_VERSION - OS X target version
• Add OPTIONAL argument to git_external. This gives users the possibility of
  cloning a repository without aborting the configuration if the operation fails
• Coverage.cmake fixes:
  • Fix missing coverage report for multiple project directories
  • Rename targets to match PROJECT_NAME-target syntax
  • Exclude only generated files from COMMON_GENERATED_FILES property,
    not everything from PROJECT_BINARY_DIR
• Added new test targets called nightlytests and Project-nightlytests. This
  targets depend on perf tests, and cpp test files with the prefix "nightly".
• Add c++11 noexcept test (CXX_NOEXCEPT_SUPPORTED define)
• Add Findhttpxx.cmake
• Add Sanitizer.cmake for gcc and clang runtime sanitizer support
• Add CoverageGcovr.cmake for gcovr support
• FindGLEW_MX considers GLEW_ROOT as environment and CMake variable
• Fix install in common_library() with subfolders
• Ignore moc and qrc files in coverage report
• Make CPACK_RESOURCE_FILE_LICENSE configurable
• New CompilerIdentification.cmake, resulted from splitting Compiler.cmake
• Remove Findzeromqcpp.cmake, use Findlibzmq.cmake instead
• Remove obsolete GIT_TARGETS_RELEASE_BRANCH
• Remove -DBOOST_TEST_DYN_LINK from all translation units