create .travis.yml

Tests should be passing in 3.4, but failing in 3.3 and 3.2.
travis needs to install realpath
compat.makedirs
store PLUGINS_DIR at load time

With this commit, peru is Python 3.3 compatible again. We should add
integration tests to enforce this going forward.
avoid subprocess.DEVNULL (for 3.2 compatibility)
compat.indent()

With this diff, peru is compatible with Python 3.2. We still need to add
integration testing to enforce this.
test_compat.py