feat(plug-in): close watchers when karma exits
docs(CONTRIBUTING): add contributing guide
chore(project): release v0.6.2
docs(README): add maintainer section
docs(CONTRIBUTING): typo and grammar edit
fix(travis): make node version a string

This is a common mistake with Travis files. It used to not cause problems but apparently they now changed something. YAML parses `0.10` to `0.1`. Either Travis or nvm used to assume this meant `0.10` but apparently now it breaks. Strings are always the right convention anyhow since version numbers aren't actually numbers.
feat(plug-in): add browserify 5.x support (WIP)

Related to #12
feat(plug-in): add file to bundle before require

Otherwise transforms don't run