* Adds a callback function to a specific programmatically triggered tag (hook)
* @param tag - the hook name
* @param callback - the callback function variable name
* @param priority - (optional) default=10
* @param scope - (optional) function scope. When a function is executed within an object scope, the object variable should be passed.
WPD.Hooks.addFilter = function( tag, callback, priority, scope )
* Removes a callback function from a hook
* @param tag - the hook name
* @param callback - the callback function variable
WPD.Hooks.removeFilter= function( tag, callback )