no RENAME option on older CMake versions

The RENAME option for install(TARGETS ...) does not seem to be available
on all CMake versions.
Fix shared library and python module

Conflicts:
	src/CMakeLists.txt
python module file suffix is platform dependent
Merge remote-tracking branch 'kljohann/python' into dev/travis
Merge branch 'pull/python_default_scope' into dev/travis