Application installer add extention to my browser. Is mavericks following the path of Windows?
During installation many installers, not just uTorrent. (Also Daemon Tools for example on Windows) try to install a lot of stuff on your computer.

If you accept one of the offers (which looks like an agreement), you end up with stupid plugins in your browser and other default search tools - this is exactly what you're facing right now.

I would strongly recommend you to open the installer again and notice the 3rd party installers which are hidden inside the uTorrent installation program so you can spot them in future installations.

For now, to fix this problem: Remove the toolbars / plugins manually and set back Google (or whatever your default search provider was) as default search engine.

To make this answer complete, the same could happen to you on Snow Leopard. This is just the way the installer (ab)uses the way you grant access in installing an application as Administrator.