Change default congress port to non reserved port number 1789

This patch changes the default port number congress-server uses from 8080
to 1789 which is not reserved by anyone yet. 1789 is also the date that
the United States Congress was created so this number seems like a good
fit.

Change-Id: Ie3cf2639408cf3aa8d2cb64532871835f1cdf0d1
Closes-bug: 1364126
Merge "Change default congress port to non reserved port number 1789"