Avoid using whitespace in test_safe_parse_xml.

Updates our MiscellaneousXMLUtilTests.test_safe_parse_xml test
so that it avoids using and ignores whitespace. This works around some
minidom parsing differences that can happen with some versions of python
2.6.

Fixes LP Bug #1158826.

Change-Id: Iada0b095ab3b5ac6dc026b3ff6cdfb175f1e20a7
Merge "Avoid using whitespace in test_safe_parse_xml."