Update overall_header_stylesheets_after.html

Add the option to set extra options for google analytics after create, so other extensions can add tracking options (Like adding the ability to track advertisements). See here for a example: https://support.google.com/analytics/answer/2444872?hl=en&utm_id=ad
Merge pull request #34 from paul999/patch-1

Update overall_header_stylesheets_after.html