Alter the script before being sent

Motivation:

I had to use Google Analytics content group, and in order to do so I had to add ga('set',...) before the data is being sent to GA (e.g. ga('set', 'contentGroup1', 'Men');).

Solution:

I've added a new hook to called hook_googleanalytics_before_send_alter(&$script), which allows us to alter the script before it is being sent to google.
The new hook may be used in a various situations:

1. set content groups
2. set other page data
3. ...

Thanks,
Rotem