cutils: Add property_get_bool, _get_int32, _get_int64

* Read out system properties with same syntax as SystemProperties.java
* Also adds unit test suite to validate correctness of properties
* Also fixes buffer overrun in property_get

(cherry picked from commit d4507e92)

Change-Id: Ifd42911f93e17da09e6ff1298e8875e02f3b6608