Gitian builds for 3.0-alpha-3

I just finished building the bundles for 3.0-alpha-3. They are available at https://people.torproject.org/~sukhbir/3.0-alpha-3/. I have also signed them.

Just a note though: seems like NoScript was updated after 3.0-alpha3 was tagged and so there was a hash mismatch during the build process. I updated the hash locally (in the versions file) and the above built is based on the latest version of NoScript. (The hash of the latest version is not in the builders/tor-browser-bundle.git repository yet.)