Merge pull request #1408 from Martynas-P/master

Update PayPal's and Amazon Payments' buttons
Trailing whitespace removed in /admin php files

More code cleanup @jamesallsup
Merge pull request #1409 from opencarthelp/master

Trailing whitespace removed in /admin php files
Merge pull request #1410 from Martynas-P/master

Ported PP Express' changes from 1.5.6 to 2.0
Added Amazon Payments module.
Merge branch 'master' of https://github.com/Martynas-P/opencart