Blueprint has a generic AppendProperties/AppendMatchingProperties now,
use it, and replace all bool properties that might be modified by a
mutator with *bool, which provides the correct replace-if-set semantics
for append.
Also remove uses of ContainsProperty except when explicitly checking if
a property was set in a blueprints file.
Change-Id: If523af61d6b4630e79504d7fc2840f36e98571cc
06a931bdb6