Fixing BCWarehouse::all()

Calling all() on BCWarehouse now returns the array of all BCs added
to the warehouse.

Refs #3692
Merge pull request #4354 from andrsd/bc-warehouse-all

Fixing BCWarehouse::all()
Add switching and barrier function materials (#4355)
Register materials and add test (#4355)
Fix indentation, use switch (#4355)
Add Constraints to the _all_objects vector.

This way, they are returned correctly by Warehouse::all().

Refs #3692
Merge pull request #4357 from dschwen/pfswitch_4355

Add switching and barrier function materials
Add InitialConditions to the _all_objects vector.

This way, they are returned correctly by Warehouse::all().  I don't
actually know if this is useful, though, since there are several
different types of ICs and they can be block-restricted and inactive.
Also, ScalarInitialiConditions are not InitialConditions, so they
can't be stored in the _all_objects vector of the
InitialConditionWarehouse.

Refs #3692
Merge pull request #4358 from jwpeterson/warehouse_fixes

Warehouse fixes
Adding FIXME.
Silence compiler warning about comparison of integers with different sign.

Refs #1777.
Get the refinement state of elements in the non-displaced mesh.