TBB-3.0-beta-1 include a non-stripped firefox binary

There have been two firefox binaries in TBB for a while, firefox and firefox-bin. Today, while messing around with Selenium for BridgeDB/TBB tests and trying to drive TBB from a sandboxed pypy, I noticed that one of these binaries is now non-stripped. My 3.0.2-alpha's firefox-bin is still there, but stripped, so I assume this was introduced in 3.0.3-alpha to build with the detached debugging symbols. We shouldn't ship a non-stripped binary, even if it's not being used.

I think, to fix this, some changes might need to be made to the gitian-builder to get it to toss out the non-stripped binary, or just not package it.