0.16.0

Features:

• Add parameters argument to Blueprint.route to pass documentation for
  parameters that are shared by all operations of a path (:pr:78).

Other changes:

• Backwards-incompatible: Bump minimum apispec version to 2.0.0.
• Backwards-incompatible: Path parameters documentation passed in
  Blueprint.doc is no longer merged with automatic documentation. It should
  be passed in Blueprint.route instead.
• Backwards-incompatible: Remove Api.schema and Api.definition.
  Those methods are useless since Schema components are automatically
  registered by apispec. Manual component registration is still possible using
  the internal apispec Components object. (:pr:75)