Take wmsResolutionHint into account

PR https://github.com/camptocamp/c2cgeoportal/pull/582 adds wmsResolutionHint to WMTS layers in the "theme" object. This CGXP PR uses that property to avoid making WFS/box queries for layers that are "out of range".

This PR will conflict with #447. I think we should address and merge #447 first. I can then rebase my resolution-hint branch onto the new master.