Test revoke a privilege from a role using a different grant path.

Conflicts:
	test/box/bsdsocket.result
	test/box/bsdsocket.test

Conflicts:
	test/box/bsdsocket.result
	test/box/bsdsocket.test

Implement granted privilege cache in struct user.

Reload user privileges from system spaces and
rebuild the cache whenever a grant or revoke occurs..

Implement revoking privileges from a role.
Basic tests pass.

Do not rebuild the privilege cache of objects
for which it can't have changed with a grant
or revoke.

Optimize rebuild_effective_grants().

Make role.test idempotent.

Make grant and revoke robust to malformed arguments.
Fix bugs in schema.lua, related to incorrect arguments
for grant/revoke.

Added method remote:reload_schema()

Conflicts:
	doc/user/connectors.xml
	doc/user/stored-procedures.xml
	doc/user/tutorial.xml
	src/coio.cc
	src/evio.cc
	src/evio.h

Provide fine-grained keepalive options on Linux, which
supports per-socket defaults.

Fix a bug with trying to set keepalive options for UDP
sockets - don't try to do it.