Promisify with whenjs
Switch to bluebird promises and reql-then

This allows promisifying an object such as cursor.toArray
Switch from rql-promise to rql-then

rql-then uses bluebird underneath and this streamlines the dependencies.
Remove unused code
Convert tableList to promises
Convert queriesList to promises
Promisify more of the code
Promisify distinct value of table

This is part of the road for issue #24
It is now possible to run the distincts() method for a query on any
query type.