Report code coverage for front-end unit tests

[treyhunner]

• Generate code coverage reports
• Report code coverage to coveralls

[coveralls]

Changes Unknown when pulling cae7457 on add-backbone-code-coverage into * on master*.

[treyhunner]

This is ready for code review

[goldlilys]

When I run gulp test, all tests pass but the coveralls has errors

ERROR [coverage]: [TypeError: Cannot call method 'split' of undefined]
TypeError: Cannot call method 'split' of undefined
at HtmlReport.Report.mix.writeDetailPage (/Users/goldlilys/dev/start/week7/fullstack-project-01/node_modules/karma-coverage/node_modules/istanbul/lib/report/html.js:391:31)
at /Users/goldlilys/dev/start/week7/fullstack-project-01/node_modules/karma-coverage/node_modules/istanbul/lib/report/html.js:468:26
at SyncFileWriter.extend.writeFile (/Users/goldlilys/dev/start/week7/fullstack-project-01/node_modules/karma-coverage/node_modules/istanbul/lib/util/file-writer.js:57:9)
at FileWriter.extend.writeFile (/Users/goldlilys/dev/start/week7/fullstack-project-01/node_modules/karma-coverage/node_modules/istanbul/lib/util/file-writer.js:147:23)
at /Users/goldlilys/dev/start/week7/fullstack-project-01/node_modules/karma-coverage/node_modules/istanbul/lib/report/html.js:467:24
at Array.forEach (native)
at HtmlReport.Report.mix.writeFiles (/Users/goldlilys/dev/start/week7/fullstack-project-01/node_modules/karma-coverage/node_modules/istanbul/lib/report/html.js:461:23)
at /Users/goldlilys/dev/start/week7/fullstack-project-01/node_modules/karma-coverage/node_modules/istanbul/lib/report/html.js:463:22
at Array.forEach (native)
at HtmlReport.Report.mix.writeFiles (/Users/goldlilys/dev/start/week7/fullstack-project-01/node_modules/karma-coverage/node_modules/istanbul/lib/report/html.js:461:23)
at HtmlReport.Report.mix.writeReport (/Users/goldlilys/dev/start/week7/fullstack-project-01/node_modules/karma-coverage/node_modules/istanbul/lib/report/html.js:553:14)
at /Users/goldlilys/dev/start/week7/fullstack-project-01/node_modules/karma-coverage/lib/reporter.js:138:24
at Object.oncomplete (fs.js:108:15)

DEBUG [launcher]: Process Chrome exited with code 0
DEBUG [temp-dir]: Cleaning temp dir /var/folders/g7/f6s075793fg7b9spwxnrqp_w0000gn/T/karma-55211399
INFO [coveralls.io]: uploading...
INFO [coveralls.io]: 422 --- {"message":"Couldn't find a repository matching this job.","error":true}

I redid npm install, but did the same thing.

[treyhunner]

@goldlilys coveralls isn't supposed to work locally. We could use an environment variable to disable it locally. @tbashor @michaelerobertsjr thoughts on that?