Update API in Suitcase

[licode]

Some thoughts on how to do preprocessing on the data. Thanks for suggestion from @tacaswell

[licode]

@stuartcampbell

[hhslepicka]

@licode, since we create the data broker with mds, fs can we just use the db instance at the export function?

[licode]

Now we may have multiple databrokers, so it is better to define it explicitly as an input. But it is better to pass in db instead of db.mds in case we want to use other functions from db.

[hhslepicka]

Exactly! =)

[danielballan]

@licode Did this code get ported to the suitcase repo?

[licode]

right, this is the doc for a new PR in suitcase. I will do rebasing here.

[danielballan]

What's the status of this? Is this still relevant given our new plans for suitcase, @licode?