Have name field as default config

Exctract hard coded creation to default config for name field.
D8 readiness for contacts module

Ported basic features of the contacts module to Drupal 8 API
Just simple lists, no views integration for now
D8 readiness for activites module

Ported basic features of the activites module to Drupal 8 API
Just simple lists, no views integration for now
Introduce a matcher service
Move match classes and interfaces

Move to psr-4
Prepae match fields to become plugins
Make matching rule configuration a config entity
Convert matching rule configform
Add match field plugin

Added plugin manager and annotation for match fields.
Updated interface and base class.
Made unsupported field a plugin.
Add annotation for text match field
Prepare to make engines plugins
Discover engines as plugins

Added plugin manager
Added annotation
Changed matcher to use plugin manager to get the engines.
Add engines config form
Make default engine a engine plugin

Added annotations
Moved to correct namespace
Cleaned up the base engine class
Convert "Default matching engine configuration" page