CRM/Core/Component.php should load only active components

Currently, the function getComponents() in CRM/Core/Component.php loads all civicrm components, even if they are not active (via the admin settings).
It might provide a small performance boost if the function loads only the necessary components.

The function is called when we do API calls (ex: civicrm_contact_get).

Sample patch attached. (works for me on a production site, I moved CRM/Pledge out of my web directory, and the site does not cause an error)

matt (bgm on #civicrm)