Add an attribute to ngeo-wmts-get-cap to save capabilities URL
Add an attribute to ngeo-wmts-get-cap to save capabilities URL

If ngeo-wmts-get-cap-url is not present, capabilitiesUrl is undefined in the configuration of the layer.

Close #2622

adube/ngeo,camptocamp/ngeo,adube/ngeo,camptocamp/ngeo,adube/ngeo,adube/ngeo,camptocamp/ngeo,camptocamp/ngeo,camptocamp/ngeo