(PUP-3315) Ask for master's FQDN

Previously, the MSI asked for the puppet master's hostname, but it
really needs to be the FQDN, so that it matches the server's SSL
certificate.

This commit updates the text in the MSI installation dialog box.
Merge pull request #77 from joshcooper/ticket/master/PUP-3315-fqdn

(PUP-3315) Ask for master's FQDN