Improved currency update method to include curl timeouts, to handle occasional timeout issues. Closes #1230
Updated SQL mode in install SQL file and MySQLi adapter to accommodate servers that have strict mode enabled by default. Ref: #1347

Removed Amazon payments xls file from system folder as it can be downloaded online and has no place in the code framework.
more custom fields done
Merge branch 'master' of https://github.com/opencart/opencart
more custom field work done