feat(githooks): adds commit-msg hook.

Uses a python script to validate commit messages against a modified
version of Angular's guidelines

#! GIT COMMIT MESSAGE FORMAT ERRORS:
#! https://docs.google.com/document/d/1QrDFcIiPjSLDn3EL15IJygNPiHORgU1_OOAqWjiDU5Y/edit#
#! Line 3: No line should be over 72 characters long. (is 75)