minor docs updates

- Updated the Java wrapper URL
- Added a note to the Components API stating only Allocations API
supports proration
- Spelling correction on Gateway Config page
- Moved “Enable Coupons” section from Hosted Page Settings to Product
Options
- Fixed incorrect id under Read Component For A Product Family
How about a warning banner that says:

"The Components API is deprecated and will not receive new features.  Chargify will continue to support it until further notice.  For new development or updates, please use the Allocaitons API instead"