Add missing request dependency

[rogatty]

Bot is failing with:

Jan  9 11:07:27 dev-adeng sandbot: Error: Cannot find module 'request'
Jan  9 11:07:27 dev-adeng sandbot:     at Function.Module._resolveFilename (module.js:536:15)
Jan  9 11:07:27 dev-adeng sandbot:     at Function.Module._load (module.js:466:25)
Jan  9 11:07:27 dev-adeng sandbot:     at Module.require (module.js:579:17)
Jan  9 11:07:27 dev-adeng sandbot:     at require (internal/module.js:11:18)
Jan  9 11:07:27 dev-adeng sandbot:     at Object.<anonymous> (/usr/wikia/sandbot/index.js:4:15)

Let's add the missing dependency.