Significant enhancements

Thanks for the module. I'm testing mouseflow, and as part of the testing I significantly enhanced your module:

• You can now specify which roles will have the JavaScript included. If no roles are specified, everyone will have it included in their pages.
• You can now specify which pages should include or exclude the script. In addition to specifying paths, you can specify PHP. This works just like how you specify when a block should be displayed. In fact, I took this functionality from the blocks module.
• I spelling and grammar mistakes.

I've attached my version. Hope you like it and can merge it.