cleanup of indexes, fix for compaction (hash, cap, geo)

Conflicts:
	arangod/VocBase/compactor.c
	arangod/VocBase/document-collection.c
	arangod/VocBase/synchroniser.c
	arangod/VocBase/vocbase.c
Merge branch 'devel' of github.com:triAGENS/ArangoDB into devel