WIP on 3272-db-config
Merge branch 'reql_admin' into tim/3272-db-config

This commit still doesn't compile (tim/3272-db-config didn't compile before, so it's OK)

Conflicts:
	src/clustering/administration/real_reql_cluster_interface.cc
	src/clustering/administration/real_reql_cluster_interface.hpp
Make db_config() porcelain work.
Don't try to use table_meta_read() for db_config
Fix style issues in interface.db_config test.
Merge branch 'tim/3272-db-config' into reql_admin

Conflicts:
	drivers/python/rethinkdb/__init__.py