Changed order of settings fields

Moved 'active' to top, 'logourl' to second in settings fields order.
Moved 'logourl' setttings field

Pushed 'logourl' further down in the settings field order.
Changed description

Updated the Options description to give better information to the user.
Updated comment

Changed comment at the end of cc_relogo_logourl_callback to be more
accurate and informative.
Added callback for 'active'

Added setting callback for 'active' settings field.
Added entry for 'active' in settings validation

Added support for 'active' settings field in settings validation
function. This value is passed directly to the database as it needs no
validation.