Add plugin for Sencha Touch.

Should be able to check for:
  Sencha 0.9 beta
  Sencha 1.0
  Sencha 1.1.0+
  Sencah 2.0.0+

We could add another check doing an `indexOf` over each script elms's `src` from `document.scripts`. But this test works on all the versions of Sencha Touch I could find in the wild.