Make Makefile and make/make.py more uniform and apply DRY.

So anything that runs in a Python process is done from make.py
(nose and flake). Makefile uses make.py in these cases.

Also make command names the same.
No FileNotFoundError on py 2.x
Merge pull request #148 from vispy/more-uniform-make

More uniform make
FIX: No need for OpenGL beta, test old Pyglet rejection
FIX: Remove old comment
Merge pull request #151 from Eric89GXL/better-travis

FIX: Travis tweaks