Add #all_values

It will merge #all_attributes and #all_associations and return one hash
with both.
Renaming #all_values to #all_associations_and_attributes to improve readability and remove some umbiguous issues
Remove gem update from travis build

This were being executed to fix an issue related to rubygems
(https://github.com/rubygems/rubygems/pull/763).
This was fixed and merged 8 months ago and this code is breaking some
build on Travis because of timetouts.
Merge pull request #71 from zertico/travis_fix

Remove gem update from travis build
Merge pull request #70 from zertico/all_values

Add #all_values