Fix tests to work with current webassets==dev

* Remove TestVersionSystemDeprecations test class.
  Webassets 0.7 deprecation warnings are removed at
  miracle2k/webassets@29d393a55bdd1b5bce170e7a6032c0764a15e112.

* Use url_expire option instead of removed expire option
  to preserve test outputs.

* Remove py25_flake08 env from tox.ini and .travis.yml.
  268e83f1167ce45ac5b36048461370e9c5a84f54 has already dropped
  Python 2.5 support
Require pyScss==1.1.5 to test test_filters.py
Don't skip test when Flask 0.10

Just don't skip test, since Flask-Assets requires at least Flask 0.8.
Fix test_glob()

Bundle.urls() returns a unsorted list.
Merge pull request #47 from papaeye/fix-tests

Fix tests to work with current webassets==dev