Refactoring & new features: Band imagery opacity and scale altering

This request refactors quite a bit of the logic for applying the transformations in order to support new features.

Two new features were added:
* Transform Scale
* Transform Opacity

In addition, the plugin is more extensible so support for other transformations can be added.

The CSS classes were modified to make more sense. Most elements need to have the wdn-scroll-watch class added. See the examples for additional details.

Samples available here:
http://ucommbieber.unl.edu/workspace/wdntemplates/sandbox/band-imagery.shtml