Fix jsx "line too long" error to match format

Summary:
The line length error had a different format than the others (no error
code) which caused it to not be caught by arc lint.

This adds in the error code and puts the original message (from
https://github.com/jshint/jshint/blob/85b5b59474d278a0afa85c3a0f0ff125038fcd05/src/messages.js#L176)

Test Plan:
* Go to a repo with jsx code
* Make a line that is too long (>=80 chars)
* run arc lint <that file>
* it should complain about the line being too long

Reviewers: alex, alpert

Reviewed By: alpert

CC: joel

Differential Revision: http://phabricator.khanacademy.org/D6137