Ensure dict orders are deterministic

Python 3 enables hash randomization by default, additionally tox 1.7
turns on the same randomization for earlier versions of python by
default. Need to ensure that order of iteration over the yaml data and
resulting XML has deterministic order for testing.

Adapts https://gist.github.com/enaeseth/844388 which ensures data read
by yaml will have its order retained in a predictable manner across
multiple python versions.

Additionally it seems more sensible to ensure that the order of
generated XML snippets corresponding to the input yaml files are
consistently in the same order as the entries in the source files.

Closes-Bug: #1333349
Change-Id: I6bf6d298a2609cc6ddbbc6b02b7f1a04413a5c89
Merge "Ensure dict orders are deterministic"