Up version to 3.0.4
Fix inconsistent tile height artifact in Chrome

Round tile coordinates and dimensions to stop undesired varying appearance of tile heights.
Update README

New description, running locally instructions, and license.
Rename README.markdown to README.md
Rename LICENSE to LICENSE.md
Rename CONTRIBUTE.markdown to CONTRIBUTE.md

-2014
Add webpack-dev gulp task
Add note in README for running non-minified build
Move Chrome bookmark functions into new file