Remove logic for running a file after translation

Bug #373
Merge branch 'only-type-check-373' of https://github.com/iankronquist/mypy into iankronquist-only-type-check-373

Conflicts:
	scripts/mypy
Clean up command line option handling

Remove -S option and simplify --py2 to not take an interpreter.
Better usage for the mypy script
Update example in README

Make it more interesting.
Update README to not say that 'mypy' runs programs
Minor tweaks to README