Fix failing compare_trajectories.py tests

Since trajectory results are no longer subclasses of namedtuple in skbio, a few tests were failing that relied on sorting of tuples. The changes here should allow the tests to pass with previous versions of skbio as well as the latest release and dev versions.
Merge pull request #1602 from ElBrogrammer/compare-trajectories-fix-tests

Thanks @ElBrogrammer
Merge branch 'master' of https://github.com/biocore/qiime into add-sumaclust

merge upstream master changes to branch
code review suggestions taken into account