HPCC-8245 - Clear up a few things

1) bug, race between 1st/2nd broadcasters on different slaves
2) Ensure all members initialized in constructor
(move some things from init() to constructor in the process)
3) Clear up tabs vs spaces
4) Unify on one createLookupJoinSlave() method and use TAK type
5) Add #TEST_FAILOVER_ defines
6) Comment in JFsmart usage

Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>