Ignoring Ruby Gemset file
Update contributing section using Github Guideline.
Merge pull request #130 from pragmaticivan/feature/ignore-ruby-gemset

Ignoring Ruby Gemset file
Updating CONTRIBUTING.md, Adding link and instructions about CodeTriage.
Merge pull request #131 from pragmaticivan/feature/contributing-github-guideline

Update contributing section using Github Guideline.
[ci skip]

Fix URL removing "]"
Merge pull request #132 from pragmaticivan/feature/contributing-github-guideline

Removing "]"
Adding 'appraisals' gem for easy local testing against multiple versions
of rails.
Updating README: appraisal / compatibility.

Added instructions for running tests with appraisals.
Added section about Ruby / Rails compatibility.