Merge pull request #133 from blatyo/yaml

Add yaml check.
Update changelog.md
Fix typo (disbale -> disable)
Merge pull request #136 from edgurgel/fix-typo

Fix typo (disbale -> disable)
Added gem post install message.
Merge pull request #137 from georgeyacoub/post_install_msg

Added gem post install message.
Add scss-lint check