Make sure that property defaults are converted correctly

If a developer defines a default boolean as "true", then we really want
True when we do "self.properties['bla']" not 'true', otherwise this
is not consistent.

Change-Id: I3705e573e2fd68a04b26c5589d38f84d68641738
Partial-bug: #1375151
(cherry picked from commit 04585f6107f7851d10c5393da74a30ac1c9e2c50)
Merge "Make sure that property defaults are converted correctly" into stable/juno