Run mongodb migrations using es6

[KieronWiltshire]

I'd love for the ability to import a config file written in es6. Anyway we can do something like:

./node_modules/.bin/mm --config=./src/config/database.js --compilers js:babel-core/register

It would also be neat if we could specify in the config file what type of migration presets, you already have the coffee script in there, maybe add an es6 equivalent too?

[KieronWiltshire]

#65