BUG: let's not modify module-level globals in tests...
BUG: use mock instead of modifying module-level globals.
BUG: fix old tests to work on 2.6 as well in randomized mode.
MAINT: use randomize when running tests on travis-ci.
Merge branch 'master' into fix_tests_global_states

Conflicts:
	.travis.yml
Merge pull request #132 from enthought/fix_tests_global_states

Fix tests global states