Runtime properties may no longer have default value

Default value was ignored for Runtime properties.
Now Runtime properties get initialized automatically if they have Default key
(it may be of null value). If such property was not initialized neither by Default
value nor in initializer an exception is thrown upon access to such property.

Change-Id: Icde635015a426664c1f78f5602ae73a5cb71f76e
Closes-Bug: #1364484
Merge "Runtime properties may no longer have default value"