Update development and CI configurations

* When validating coverage, run all layers except Robot
* Run code analisys on CI
Add a list of sites using collective.cover
Minor style improvements for layout tab
Fix typo
Add Bitdeli badge
Change icons for column resize
Merge branch 'master' of github.com:collective/collective.cover
Fix image positioning in basic tiles (closes #317)
Fix image positioning on collection tile (closes #318)
Make list tile configurable (fixes #339)

You can now:

* Set the ordering and visibility for all fields
* Set the preferred style for the title
* Set the scale and alignment for the image thumbnail

The date of the items is also shown and tests were added.
Update i18n
Update changelog
Merge branch 'master' into plone-api

Conflicts:
	CHANGES.rst