Fixing issue where JSLint-parser does not find source file

Fixing an issue where JSLint parser could not locate the source file of the script. Will now attempt to find the file both in the job workspace as well as using the source paths provided in the violations configuration.

While #13 fixed the issue of the errors not being shown at all, it still only shows the errors without marking them in the file.
![violations-plugin-jslint-current](https://cloud.githubusercontent.com/assets/275651/4175404/a255a5d0-35d0-11e4-813a-04cc250b839b.png)

This patch will at least attempt to find the correct file, and show the contents like it does with other parsers:
![violations-plugin-jslint-fixed](https://cloud.githubusercontent.com/assets/275651/4175405/a7568072-35d0-11e4-8c0e-e4f9aa66a9d1.png)