Extract base layer logic to a service

Extracted base layer logic which was in map service to be able to retrieve it
from other services that may want it.

Fixes #1
Merge pull request #2 from jchapron/jc-add-baselayerservice

Extract base layer logic to a service
Hotfix: centerOn control (inverted bbox)

Fix bbox which was wrongly defined (minx, maxx / miny, maxy) instead
of (miny, minx / maxy, maxx).
Revert "Hotfix: centerOn control (inverted bbox)"

This reverts commit 9b35599db614297d9b9b7ad2d729b99d6690eefe.
Hotfix: centerOn control (inverted bbox)

Fix bbox which was wrongly defined (minx, maxx / miny, maxy) instead
of (miny, minx / maxy, maxx).
Make layer's max_zoom configurable

* Add field max_zoom to layer
* Modify backend form to make it editable
* Add field in layer serializer
* Change the hardcoded value to a dynamic one
Fix home button on catalog

Was broken, closed the catalog when query was blank even when not
at catalog's root.

Fixes #3722
"Lag" when closing sidebar

Due to legacy css transition.

Fixes #3719
Layers' order affects ZIndex and can be saved

* Modify tilelayer zindex to reorder layers
* Save position in array
* Use unshift instead of push to add new layer on top of array

Fixes #3721, #3727
Merge branch 'feature/reorder-layers'

* feature/reorder-layers:
  Layers' order affects ZIndex and can be saved
Minor changes on catalog design

* Center all elements
* Text decoration on breadcrumb links