Merge branch 'feature_dimensions' into 'development'

Dimensions middleware

This middleware is used to get the dimensions in the query parameter `dims` as an array of dimensions.

EXAMPLE USAGE:

* Use it with no parameters to get all the dimensions in the query: `app.get('/', dimensions(), function(req, res, next){})`
* Use it with an array of accepted values: `app.get('/', dimensions(['year', 'location']), function(req, res, next){})`
* Use it globally: `app.use(dimensions())`

See merge request !9