Initial Development - Common functions

[johnstray]

This issue is specifically for tracking the development of the common functions. These functions need to be written:

• init - Initialise the plugin
• main - Admin backend director
• pageDataFilter - Sets the metadata for the current blog page
• pageContentFilter - Filters page content to show the blog
• displayMessage - Displays a notification message on the backend
• debugLog - Add entry to GS debug log