Remove all tests from setup.py except those of gloo.gl

I want to inspect coverage of the gloo.gl backend tests.
Flake

Arg, I always forget this :/
Allow glGetShaderPrecisionFormat to not be available in tests.

One machine on Travis missed it according to PyOpenGL
Fix FBO issue for pyopengl backend
Fix issue related to renderbuffer on pyopengl backend
Put tests back in setup.py
Merge pull request #178 from almarklein/test-gl-coverage

Test gloo.gl test coverage