Configure Vim for editing commit messages

* Start out in insert mode because that's always the first thing I do anyway
* Wrap text at 80 characters
* Turn spell check on
Configure Vim for the Jade template language
Configure Vim for editing JSON
Configure Vim for editing LESS
Configure Vim for editing emails
Configure Vim for editing markdown
Configure Vim for editing PHP
Configure Vim for editing Ruby
Configure Vim for editing YAML