Updates to latest version of stylelint.

[manovotny]

• Adds new rules.
  • at-rule-semicolon-space-before
  • font-family-no-duplicate-names
  • rule-empty-line-before
  • selector-max-id
  • selector-max-type
• Removes deprecated rules.
  • block-no-single-line
  • custom-property-no-outside-root
  • declaration-block-no-ignored-properties
  • declaration-block-properties-order
  • media-feature-no-missing-punctuation
  • root-no-standard-properties
  • rule-nested-empty-line-before
  • rule-non-nested-empty-line-before
  • selector-no-empty
  • selector-no-id
  • selector-no-type
  • selector-root-no-composition
  • time-no-imperceptible
• Updates existing rules with newer options.
  • at-rule-empty-line-before
  • comment-empty-line-before
  • max-nesting-depth

Fixes #3