TRQ-2722. Revert a change that made it impossible to re-create a node with the same name.

If you deleted a node via qmgr and then created it the creation would always fail. Revert
the change that caused this.
TRQ-2765. Make new nodes overwrite the DNS cache if necessary.

When performing node bursting sometimes nodes are deleted and then added again but with a
different ip address (because they are VMs). To handle this, make it so that we overwrite
the DNS cache at the time that the node is added to the cluster.
Added IS_DELETE_ADDRS to the IS protocol.

IS_DELETE_ADDRS makes it possible to update all
remaining moms when a node is removed. The new
protocol command sends a comma separted list
of ip address and port and it is used to remove
the node entry from the AVL tree.
Make the okclients list get updated correctly when new nodes are added via qmgr.
Revert "Added IS_DELETE_ADDRS to the IS protocol."

This reverts commit 077ecf6e433c514797043ec151fe176d387734f7.

Conflicts:
	src/server/pbsd_main.c
	src/server/req_manager.c

Also adds code to send the updated okclients after deleting a node.
Fix some issues with deleting nodes while pbs_server is running.
Fix a problem with popping a non-existent path from the hierarchy
Fix a problem when building up the hierarchy
Add a todo comment
Reset the cache when adding trusted clients back in on the chance that one of them has a different IP address.
Fixed several unit tests.
getpeername failure was not allowing the bad socket to continue being used.
Added TTL as a node feature. (Time To Live)
Don't call getpeername when you already have the ip address.
Fixed unit tests.
Set exit_called so we don't trash the container code.
Changed a copy to a reference.
Got rid of another getpeername
ac-7546 make acl and requestid attributes.
AC-7656 Don
't allow nodes to be created or deleted when the mom_hierarchy file is present.