The RP was not properly handling the series of events:
1) When a WRVIFWHOLE is received if we are the RP,
send a pim register stop to the FHR.
2) When a register was received we were sending
a join (S,G) towards the S, then a immediate prune (S,G)
followed by another join (S,G). Just send the first join
3) Save whom we received the S,G register from so we
can use it later
4) Allow a join timer to restart itself instead
of causing a crash.
Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>