Changed response data formatting in pp express ipn.

REF: #1698
Fixed opencart.sql for CREATE TABLE oc_settings

opencart.sql file contained incorrect SQL syntax for creating DB table oc_settings. Though the DROP TABLE was added the part CREATE TABLE IF NOT EXIST was not unified with the rest of CREATE TABLE statements. Therefore I removed IF NOT EXIST part.
Merge pull request #1722 from shadyyx/patch-1

Fixed opencart.sql for CREATE TABLE oc_settings
Fixes custom fields language error.
Merge pull request #1724 from steven-wm/master

Fixes custom fields language error.
https://github.com/opencart/opencart/issues/1235
Merge branch 'master' of https://github.com/opencart/opencart
https://github.com/opencart/opencart/issues/1235
removed ckeditor to be replaced with summernote
OC-1815 - Fixing mandatory fields bug when empty. Added PayPal and cheque fields to be mandatory if selected.
Fixing tabs > spaces
Merge branch 'master' of https://github.com/david-wm/opencart into OC-1815
add the some js to auto display errors in ajax forms.
custom field fix
Merge pull request #1729 from david-wm/master

OC-1815 - Fixing mandatory fields bug when empty.
https://github.com/opencart/opencart/issues/1685
Merge branch 'master' of https://github.com/opencart/opencart