TST Add ``verbose`` argument to tests.run()
DOC Document dependencies in brew style
BLD Add Makefile

This supports 'debug' and 'tests' targets in addition to just building
ENH Better error message

Previously, when attemping save of floating point image, a Programming
Error exeption was thrown.
Merge branch 'master' of git://github.com/luispedro/imread into read-pvr-texture-files