Adding HTTP mode to HAProxy stats

HAProxy's stats interface was not launching due to the default mode
for HAProxy having been set to TCP.  This patch remedies this by
directlys setting the http mode on the listener.

Change-Id: I367473049a52bf3ca0b2ac482ddb96ee39d6e045
Closes-Bug: #1355763
Merge "Adding HTTP mode to HAProxy stats"