Fix query layer search.

Now layersConfig will contains layers defined in the layer tree
(MapServer layer or group).
External Layers are stored in a deferent variable
(externalLayersConfig).
getQueryableWMSLayers return Mapserver Layer (no group) as object or
name.
getQueryableWMSLayers is not called for layer that defined
mapserverLayers or queryLayers.
Add missing ';'
Fix container definition when using MapOpacitySlider in a toolbar
Merge pull request #471 from camptocamp/mapopacityslider-actiontarget-fix

Fix container definition when using MapOpacitySlider in a toolbar
Add travis tests
Fix Jasmin tests for LayerTree by having a correct theme.
Merge pull request #474 from camptocamp/fix-jasmin

Fix jasmin tests
Fix API documentation

cherry-pick  da0427687b34cf1cb64bd457ab4079b1aa1944cc

Conflicts:

	core/src/script/CGXP/api/Map.js
Merge pull request #464 from camptocamp/fix-getfeatures_group2

Fix query layer search.
Merge branch '1.3' of github.com:camptocamp/cgxp into 1.3
Merge branch '1.3'

Conflicts:
	.travis.yml
	core/src/script/CGXP/plugins/GetFeature.js
	core/src/script/CGXP/widgets/tree/LayerTree.js