Idea: merge host and port parameters into one

[gleichdick]

@v4hn proposed to replace both warehouse_host and warehouse_port parameters with one single generic one, e.g. warehouse_uri.
With the uri parameters, the plugins have more freedom in how and where they store stuff.
Of course, this requires the adaption of all plugins (currently mongodb, and two sqlite implementations).

[v4hn]

It would be straight-forward to add a new setParams method and keep the old one as a wrapper that would auto-construct the URI.

At least MoveIt's RViz GUI should still be adapted to use the new URI format (though we probably also want to stay backward compatible there).