Ensure AAE tree wait fails test if timeout

Some refactoring to make sure errors get reported properly when things
go wrong. Wait until functions need to assert on the return value, and
this return value is more useful if it contains errors from nodes timing
out, Bad RPCs, etc.
Replacing repl_util AAE wait with rt version
Merge pull request #543 from basho/refactor/one-wait-4-aae-trees

Merge repl and rt versions of wait until AAE trees build