Fix regressions in plugin

This will fix #46. This is funny because the fix is identical to #44, but I closed that in order to fix this and said I would look at it later.

* Fix issues described in #46
* #35 is confirmed to still be fixed
* Add support for `AppleWebKit`
* Fix Gruntfile to lint script (and fixed error caught by it)
* The IE 11 test was placed in the middle of the IE 10 tests, fix placement of that
* Update README to reflect IE 12 support
* BitDeli is no longer of use due to changes GitHub made in README images. The same data can now be viewed in the Pulse and Graphs tabs.

/cc @gabceb @bhamodi
This was left over from when I added ChromeOS support. I did not know you already converted the UA to lowercase.