Reject valid receipts from other apps -bug 1024057

Originally this bug called for validating product
IDs but I don't think that would be a problem in
practice since restoring products is heavily tied
to ID.
Consolidate init options and main settings
Merge pull request #17 from kumar303/app-id

Reject valid receipts from other apps -bug 1024057
Ensure no settings are ever undefined

This fixes 'unknown setting' errors in browsers
with missing APIs.
Remove phantom dependency -- not used anymore
Default example to pay-alt; that's all that works