added quote and surround
Remove python-coveralls from requirements.txt and add to travis.yml's after_success block.

Doing this to remove "sh" package from install since it's not compatible
on Windows.
Merge branch 'develop' of https://github.com/dgilland/pydash into pr-1
added tests for strings.quote() and strings.surround()
fixed pep8 errors
added quote() and surround() to strings.__all__
changed one-letter variable
Made surround() being safe with numbers and strings.
Made quote() being safe with numbers and strings.
Merge branch 'pr-1' into develop

Conflicts:
	pydash/__init__.py
	pydash/strings.py
	tests/test_strings.py