Update translations template (c2cgeoportal.pot)

This is done by running `python setup.py extract_messages`.
Update .po files

This is done by running `python setup.py update_catalog`.
Add "queryLayers" column to "layer" table
Add migration script for queryLayers column
Take queryLayers column into account
Update translations template for "Query layers"

This is done by running `python setup.py extract_messages`.
Update .po files for "Query layers"

This is done by running `python setup.py update_catalog`.
Grey out queryLayers for non-WMTS layer
Add admin doc for WMTS queryLayers
Merge pull request #588 from elemoine/wmts-query-layers

Add queryLayers column to the layer table