Fix versions for travis-ci

This fixes some mistakes in the .travis.yml file:

* Corrects matches so the minor gem revisions get rounded, this means 2.6.0
  for example is used.
* Adds Ruby 2.0.0 tests
* Allows 2.6.0 to fail for now, as it doesn't have create_resources.
* Removes trailing commas and arrays in functions for 2.6.0.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #140 from kbarber/maint/master/fix_travis_gem_versions

Fix versions for travis-ci