Refactor claims code out of EntityView

All code related to claims is moved into a separate ClaimsView which only
knows about a list of claims. This helps us getting rid of EntityView.

Note that lots of test code is copied from EntityViewTest which however
will be deleted once we remove EntityView so that there is no duplicate
code in the long term. Furthermore, the tests do not actually test
anything further than that the output is actually HTML. The ClaimsViewTest
can also be improved in another patch as this one would grow too big.

A problem at the moment is the ClaimHtmlGenerator which also accepts
statements which extend claims at the moment. However, when this will
change we may think of renaming this to StatementsView and only accept
statements. Or we find another way of using this to display both claims
and statements.

In future ClaimsView should perhaps only be created in ItemView and be
injected via the constructor. However, this can be done in another patch
as this one would get too big. To actually kill EntityView we have to
modify the Content classes (EntityContent, ItemContent and
PropertyContent) atm..

Change-Id: Iee15ec58f69abac9fb6a85c23d6196a309d1a651
Refactor duplicate code in EntityView and related

Change-Id: I9d181433b16c2e38ca59459aae249dd1e472b9d7
Merge "Refactor claims code out of EntityView"
Merge "Refactor duplicate code in EntityView and related"