refactor contacts info

After this refactoring we now offer 2 different ways to access contact data. You can either use the recommended
$ref entry and leave the interpretation of what happens with a specific link up to the platform you are on or you
can use the new value und protocol fields to get the "raw" data.

Reasons for favoring the first solution are things like tel: links just working on platforms like Android or
Windows/Lync. If you need to do data type things with the contacts (which is actually kinda discouraged) you
can use the raw data fields described above.

Please note that in the long run we will probably start expecting each platform to do the right thing when
it encounters an external resource while walking the API. We might add some kind of nofollow
information to links to ease the traversal to a newer API. I Don't expect this to get deprecated before we
hit 2.x so we will probably phase it out with 3.x at the earliest (if at all, who knows).
Merge branch 'feature/refactor-contacts' into develop