Issue title: webcompat.com bot mislabels website bugs
 Issue body: <!-- @browser: Safari -->

**URL**: https://github.com/webcompat/web-bugs/issues/26
**Browser**: Safari
**Version**: 7.0.2
**Problem type**: Looks like the website has a bug.
**Site owner**: No

**Steps to Reproduce**
1) File a webcompat bug on any page, choosing the "Looks like the website has a bug" option.

Expected Behavior: Bug is assigned a label to indicate the problem belongs to the website.
Actual Behavior: Bug is assigned a label based on the browser accessing the site, Safari in this case.

 Comments: 
 Comment 0: Greetings, creator! I added a safari label for you.

 Comment 1: See? See? ;-)

 Comment 2: I think @Neptr got the Safari label right... but you're spot on. We need labels for "site-owner" when that applies. I filed https://github.com/webcompat/web-bugs-issue-tagger/issues/3 to track that.

 Comment 3: Ah, now I think I understand your concern. (based on https://github.com/webcompat/web-bugs/issues/26#issuecomment-41478548).

I'm going to open a meta-bug in the webcompat.com source repo where we can discuss this: https://github.com/webcompat/webcompat.com/issues/113

{'source': 'GithubIssues', 'repo_name_with_owner': 'webcompat/web-bugs', 'issue_id': 32294676, 'repo_stars': 596.0}