Update for to use files to generate spreadsheets, etc.

This changes the plugin to retrieve the plugin spreadsheet generation
code from the WP starter app code instead of hard coding it directly in
the plugin
https://app.asana.com/0/11562549203980/11683732215326
Merge branch 'master' of github.com:cloudward/ease-starter-wordpress

Conflicts:
	admin_wizard_spreadsheet_auto_save.espx