Added error msg for missing setting & formatting

Updated $nzshpcrt_gateways array with image
Fixed incorrect API version reference
Added missing closing td element tag
Workaround for cart bug form submission error

The WP e-Commerce cart will submit the plugin settings form even if you're just enabling/disabling other plugins.  This checks for the correct submission form button value to be present before our plugin attempts so save it's own values.
Added Alex's test/live mode switch
Added text for support contact information
Added logo file for display in admin settings
Added missing testmode code
Added missing testmode code
Merge pull request #19 from ionux/master

Added Alex's test/live switch and extra support information