First version of cluster server overview
Merge branch 'sharding' of https://github.com/triAGENS/ArangoDB into sharding

Conflicts:
	js/apps/system/aardvark/clusterFrontend/js/templates/showCluster.ejs
	js/apps/system/aardvark/clusterFrontend/js/views/showClusterView.js
	js/apps/system/aardvark/frontend/scss/cluster.css
Merge branch 'sharding' of https://github.com/triAGENS/ArangoDB into sharding
Merge branch 'sharding' of https://github.com/triAGENS/ArangoDB into sharding
Merge branch 'sharding' of https://github.com/triAGENS/ArangoDB into sharding
Merge branch 'sharding' of https://github.com/triAGENS/ArangoDB into sharding
Merge branch 'sharding' of https://github.com/triAGENS/ArangoDB into sharding