remove _del call from _add

So that users can bind keydown, keypress, and keyup for the same combo.
fix purgeHotkeys to delete all

purgeHotkeys would previously miss the tail end of the array, because it was using a forward loop (angular.forEach), and the index was decrementing with each delete.
Merge pull request #27 from willhoag/multiple_binding

Multiple bindings for same key
Place cheatsheet in the body when $rootElement is document
issue #8: adding tests
argh, I really need to automate version bumps
Added: Configurable cheat sheet hotkey and its description.
added tests for #33
Merge branch 'BlackMan82-master'
Multiple hotkeys to the same callback supported

closes #15
Adds alllowIn parameter
added tests and code to ensure callback is called when mousetrap class is present
bump version
issue #18: added visibility and fade props to css
increased z-index. refs chieffancypants/angular-loading-bar#69
function signature did not match up closes #36 and closes #40
bump version 1.3.1
closes #41: expose allowIn to directives
Hide hotkeys popup until CSS is loaded

Addresses Issue #45
issue #49: del method now working correctly on arrays