Suppresses deprecation warning

Adds a `config.mock_with` block to explicitly enable `:should` syntax so Rspec doesn't complain about using `stub` with old syntax when tests are run.
Fixes spelling
Makes endpoints explicit in tests
Updates Series method names in tests

Converts any reference to `#serie_FOO` to `#series_FOO` to match the method names that are in use. Also renames the series fixture files to match this convention. Finally, everywhere a single series id is referred to in the tests, I use the word 'series' instead of 'serie'. Note, all references to the `#serie` method and its fixture file remain as is.
Merge pull request #12 from O-I/spruce_tests

Spruce tests.

Tested manually after removing Rubinius from the `.travis.yml` file. All systems cleared.