[bug 899637] Added mongodb var back into env.sample
[bug 899637] Added mongodb var back into env.sample

alicoding/login.webmaker.org,cadecairos/login.webmaker.org,digideskio/login.webmaker.org,digideskio/login.webmaker.org,alicoding/login.webmaker.org,cadecairos/login.webmaker.org