Fix #11524: python binding, properly allocate returned string.
Fix #11524: python binding, properly allocate returned string.

Bug was hidden by previous by-value semantic of TypeOf<std::string>.

Change-Id: Ia85091d61b5eed089f59b650d5a86416b96ab0e0
Reviewed-on: http://gerrit.aldebaran.lan:8080/10382
Reviewed-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>
Tested-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>

bsautron/libqi,aldebaran/libqi-java,aldebaran/libqi,aldebaran/libqi-java,aldebaran/libqi,aldebaran/libqi,aldebaran/libqi-java,vbarbaresi/libqi