Add SOLR support

[reekitconcept]

• add dependency to collective person and a person type
• add behaviour to extend person type, by default disabled
• add profile for collective.solr which will be our solr search setup for intranets
• add setup handler as added by cookiecutter

[reekitconcept]

This is ready for first review, points to consider:

• is the scaffold ok now, ie. everything removed that needs to be? @ericof
• is the included person type ok? @tisto

Right now the behavior to define extra fields in the person type is not active by default but can easily be done so from tests / demo site. - My objective is being able to demonstrate the solr sidebar facet conditions. But that can be done in different ways as well. (One possibility is city / zipcode instead of building / room. but that also requires a behavior to extend the person type.)

Further steps:

• example content with which we can demo solr, feedback of @tisto ?
• cypress tests in collective.solr based on this setup, @reebalazs.
• ... ?

[tisto]

@reebalazs adding c.person as a dependency is fine with me. I'd say let's merge this asap. Let's try to set up the demo instance and then I am more than happy to give detailed feedback and plan the next steps.