Fixes bug when plugin name file ended in m, i, or n.

This had me scratching my head for quite a while, I can tell you.
A RegEx in `Gruntfile.js` on line **54** was responsible for the reason a plugin's filename couldn't end in `*n.js`, `*i.js`, or `*n.js`, rather than `.min.js`. The problem occurs when Jasmine runs as it would simply skip the file, returning all tests as failed.

Reading the [Grunt docs](https://github.com/gruntjs/grunt/wiki/Configuring-tasks#globbing-patterns), I changed the way minified files are excluded to the ignore pattern of globbing.