Factor out WET donation slider code
Update the donation slider as it is being dragged
Hide donate button if donation is set to -bash
Various bug fixes and performance improvements
Cleanup country and state lists
Replace instance of 'Connexions' with 'OpenStax CNX'
Allow adjustable minimum donation
Merge pull request #633 from Connexions/donations

Donations Enhancements
Merge branch 'master' into staging