small usability changes

Hi, thanks for your work on this extension.

I made small changes to
* hide the "New Profile" option while not in "isOptions" mode
* when loading a Profile which does not specify a domain, fill in the location of the active tab instead of "" (but only if in options mode)

If you don't want to include these changes, I might publish my fork in the Chrome Web Store.

In the first pull request I introduced bug, this is fixed in this pull request
I tested my changes in Chrome 24 Stable on Win7.

Greetings
Chris