Use sh instead of manual subprocess

[clybob]

Use library sh instead of call manual subprocess. Documentation sh library: http://amoffat.github.com/sh/

[clybob]

The output generated by sh is bad, because Pep8 and Pyflakes don't returns exit code. It's necessary find to solve this problem before apply sh. The output generated:

-> sh.pep8('.', _out=process_output) ./code_quality_tools/tests/fixtures/pep8.py:2:1: E302 expected 2 blank lines, found 1

./code_quality_tools/tests/fixtures/pep8.py:5:1: E302 expected 2 blank lines, found 1

./code_quality_tools/tests/fixtures/pep8.py:6:17: W292 no newline at end of file

Traceback (most recent call last): File "", line 1, in File "/Users/romulo.tavares/.virtualenvs/dashboard/lib/python2.7/site-packages/sh.py", line 354, in repr try: return str(self) File "/Users/romulo.tavares/.virtualenvs/dashboard/lib/python2.7/site-packages/sh.py", line 333, in str else: return unicode(self).encode(self.call_args["encoding"]) File "/Users/romulo.tavares/.virtualenvs/dashboard/lib/python2.7/site-packages/sh.py", line 337, in unicode if self.stdout: return self.stdout.decode(self.call_args["encoding"]) File "/Users/romulo.tavares/.virtualenvs/dashboard/lib/python2.7/site-packages/sh.py", line 280, in stdout self.wait() File "/Users/romulo.tavares/.virtualenvs/dashboard/lib/python2.7/site-packages/sh.py", line 266, in wait self._handle_exit_code(self.process.wait()) File "/Users/romulo.tavares/.virtualenvs/dashboard/lib/python2.7/site-packages/sh.py", line 275, in _handle_exit_code self.process.stderr sh.ErrorReturnCode_1:

RAN: '/Users/romulo.tavares/.virtualenvs/dashboard/bin/pep8 .'

STDOUT: ./code_quality_tools/tests/fixtures/pep8.py:2:1: E302 expected 2 blank lines, found 1 ./code_quality_tools/tests/fixtures/pep8.py:5:1: E302 expected 2 blank lines, found 1 ./code_quality_tools/tests/fixtures/pep8.py:6:17: W292 no newline at end of file

STDERR: