C++ error when attempting to use boost libraries with C++11

Issue

• When trying to use the boost libraries with C++ 11, we get the following error:

`/usr/include/boost/date_time/local_time/custom_time_zone.hpp:67:30: error: cannot convert ‘const boost::shared_ptr<boost::date_time::dst_day_calc_rule<boost::gregorian::date> >’ to ‘bool’ in return`