Flake8, Semver, Pre-commit

* Added pre-commit: http://pre-commit.com
* Fixed flake8 errors
* Added flake8 pre-commit hooks
* Added pre-commit to Makefile
* Changed VERSION numbering
* Changed versioning to match PEP-0440

tests/test_plugins.py

@@ -1,15 +1,11 @@
 #!/bin/env python
 
 import os
-import logging
 import pickle
 import shutil
 import tempfile
 
-import json
-import os
 from unittest import TestCase
-from flask import Flask
 from senpy.models import Results, Entry
 from senpy.plugins import SentimentPlugin, ShelfMixin