added several AQL functions
Merge branch 'devel' of https://github.com/triAGENS/ArangoDB into aql-functions
Merge branch 'devel' of https://github.com/triAGENS/ArangoDB into aql-functions

Conflicts:
	CHANGELOG
renamed function, updated documentation
Merge branch 'aql-functions' of https://github.com/triAGENS/ArangoDB into devel
issue #1109: added *bytes* unit to API description where missing