Allow choice of rotation; clockwise/anticlockwise

Fixes #105

Creates the `rotation` option that allows a setting of `anticlockwise`
(or 'acw') to reverse the direction of progression used by the knob. It
fully supports the clicking/touching and `displayPrevious`
functionality.

To facilitate extending this behavior to custom draw functions, arc
calculations have been factored out of `draw` into an `arc` function,
which returns the start and end angles, and a boolean denoting the
direction of the stroke.
Update tron skin to use new arc function
Add an example of the rotation option
Merge branch 'issue-105' of https://github.com/mal/jQuery-Knob into mal-issue-105
1.2.8
iPod example default value
Fix IE11 beginPath #198 #194
Add UMD declaration

In order to require this plugin using Require JS or another AMD system
both this plugin and JQuery itself must be AMD-compatible. This PR adds
the Universal Module Defintion pattern from https://github.com/umdjs/umd
so it works as expected with AMD and with traditional methods of
inclusion.
loosen jquery version dependency

The previous jQuery version dependency tied the plugin to version 1.7,
not 1.7.1 or higher. I'm assuming this is compatible with 2.X too, so
loosened it to >=1.7. If it's not 2.X compatible, you could tighten it
to ~1.7 for all 1.X releases after 1.7
Merge pull request #202 from fidothe/add-UMD-declaration

Add UMD declaration
Merge pull request #204 from fidothe/fix-jquery-bower-dep

loosen jquery version dependency
Merge pull request #1 from aterrien/master

Fork newest version