paypro: example - use strict paypro headers.
Made the error message when we encounter an unknown script pubkey more clear.
Revised error message per feedback on PR.
Merge pull request #492 from curtislacy/Pubkey-Error

Clarified error message when we encounter an unknown script pubkey
paypro: fix readme file for better explanation.
paypro: example - add extra arguments for experimentation.
paypro: example - explain extra arguments in readme file.
paypro: example - add --address and --pubkey options. document in readme.
paypro: example - add privkey option. refactor.
paypro: example - remove some comments.
paypro: example - fix request method.
paypro: example - allow user to set options when using example as a module.
Merge pull request #493 from chjj/fix_paypro_example

Fix Payment Protocol Example
paypro: example - allow more modularity concerning options.
paypro: example - document modular usage of example.
paypro: example - fix customer createTX for browser.
paypro: example - remove old createTX.
Merge pull request #494 from chjj/fix_paypro_example2

Fix Payment Protocol example in the browser
Merge remote-tracking branch 'upstream/master'