Reverted R version back to 2.12.0 for now.

PICRUSt and QIIME builds are often hanging indefinitely, and after discussing with @gregcaporaso, we decided to revert for now since we have a QIIME release on Monday. We can then look into the failures and upgrade the version after the release.

I'll do a bit more debugging on my end and post details in a separate issue.
Merge pull request #52 from jrrideout/r_version_revert

Reverted R version back to 2.12.0 for now.
Add emperor to the dependencies list

Add the emperor git repository so people can start using it right away
when they install QIIME.
Merge pull request #53 from ElDeveloper/emperor

Add emperor to the dependencies list