Update Readme.md

Remove old section named Github! Change to Collaboration
patch for http proxy setting
Merge branch 'http-proxy-for-facets' into release/0.1
first try
Merge remote-tracking branch 'origin/release/0.1'
Merge branch 'develop' into DDBNEXT-25
Merge branch 'develop' into DDBNEXT-25
some refactoring
further work on item hierarchy
replaced with version from "develop"
made image path relative
renamed "parent" into "parents"
renamed "parent" into "parents"
further work on item hierarchy
Merge branch 'master' of https://github.com/Deutsche-Digitale-Bibliothek/ddb-next into DDBNEXT-25

Conflicts:
	grails-app/services/de/ddb/next/Facets.groovy
refactoring because of code review
Merge branch 'DDBNEXT-25' into develop

Conflicts:
	grails-app/controllers/de/ddb/next/ItemController.groovy
	grails-app/views/item/item.gsp