Do not assume order of new_peers list elements

This fixes the vpn unit test that breaks with a randomized PYTHONHASHSEED
(see the bug report).

The test assumed that the new_peers list from self.new_update_request had
elements in a particular order. Found with PYTHONHASHSEED=2455351445.

The fix refactors the test case to handle an unsorted new_peers list by
sorting it before running the test.

Partial-bug: #1348818

Note: There are several other unrelated unit tests that also break with a
randomized PYTHONHASHSEED, but they are not addressed here. They will be
addressed in separate patches.

Change-Id: I86e7f84cedbdc8e1d7404363a560fd759d264c49
Merge "Do not assume order of new_peers list elements"