Local Launcher Load Balancing Support

[MariaSemple]

Implement load balancing support for the SDK-based Local Launcher, per the existing implementation.

Requires NodeManager or equivalent. The root directory for writing information is <scratch-path>/[jobs|output]/<hostname> .

The plugin is already writing output and job information to the correct location. It should also write network information to the <scratch-path>/jobs/<hostname>/addrs file. It should read additional node network information from the same file for different hostnames.

The plugin needs to use the network information to pull request information from the other Local Plugin nodes in the load balanced cluster.