Make RequestContextBuffer methods chainable.
attempt to fix host test
changed Makefile for tests
changed interface for locking

Conflicts:
	arangod/VocBase/transaction.cpp
Merge branch 'devel' of https://github.com/triAGENS/ArangoDB into aql2
test fix
Merge branch 'devel' of https://github.com/triAGENS/ArangoDB into aql2