Updated changelog for version 2.4b5
For some reasons this file was not merged in PR #1811
Update views.py
Merge pull request #1868 from Geode/making-abstract-optionnal-for-external-catalog

as for wms, adding default value for catalog abstract field when creating catalog remote service (not null by datamodel)
Bumped version dependency for OWSLib
Merge pull request #1872 from gamesbook/ows

Bumped version dependency for OWSLib