This patch fixes watch registration through the config file and a broken log line when the watch registration fails. It also plumbs all the watch loading through a common function and tweaks the
unit test to create the watch before the reload.
This patch removes duplicate internal copies of constants in the structs
package which are also defined in the api package. The api.KVOp type
with all its values for the TXN endpoint and the api.HealthXXX constants
are now used throughout the codebase.
This resulted in some circular dependencies in the testutil package
which have been resolved by copying code and constants and moving the
WaitForLeader function into a separate testrpc package.
When a -dev agent is restarted it'll have a clean state, including a
reset index. A watch() will reconnect after a restart, but it won't
notice that the index counter has reset and it will keep waiting until
we reached the old index again, which is wrong. Resetting the index will
prevent that and makes watch work for -dev agents.
