3.0.0

Major changes:

• Update pip-tools for native pip 8, 9, 10 and 18 compatibility, un-vendoring pip to use the user-installed pip (#657 and #672).
  Thanks to @techalchemy, @suutari, @tysonclugg and @vphilippon for contributing on this.

Features:

• Removed the dependency on the external library first (#676). Thanks @jdufresne