Use jhpulse hostname instead of hardcoded IP

This patch uses `jhpulse.johnshopkins.edu` instead of a hardcoded IP in `jhpulse.cfg`. 

@ddagunts Mentioned the following practical and security concerns with using the `jhpulse.johnshopkins.edu` hostname, but it appears that the IP address is now changing very frequently:

> Anyway, ncui and ncsvc sometimes break DNS before jhpulse.johnshopkins.edu is resolved. For this reason we connect to the VPN by IP. It is specified in the file jhpulse.cfg. It is set to 128.220.225.216. The new address is 162.129.253.216 - fix the jhpulse.cfg file and the VPN will work. Ignore the .cert file - it will get a cert for that IP automatically. I strongly recommend using an IP address over using jhpulse.johnshopkins.edu - primarily because of the DNS issue and secondarily for security in hostile networks (DNSSEC + DANE would be even better but I'm not sure we have that implemented server-side, not sure if Juniper's client has that implemented in the software, and it you'd have to make a LOT of changes to the whole wrapper script to fix the DNS issue...)