Implement role 'replication'. Fixes gh-660.

extra/schema_fill.lua

src/box/bootstrap.snap

src/box/box.cc

test/box/access.result

test/box/access_bin.result

test/box/access_misc.result

test/box/access_misc.test.lua

test/box/bootstrap.result

test/replication/cluster.result

test/replication/cluster.test.py

test/replication/consistent.test.lua

test/replication/hot_standby.result

test/replication/hot_standby.test.lua

test/replication/init_storage.result

test/replication/init_storage.test.py

test/replication/readonly.result

test/replication/readonly.test.py