MINIFICPP-1266 - Always initialize configure_ in ProcessContext
MINIFICPP-1266 - Always initialize configure_ in ProcessContext

Signed-off-by: Arpad Boda <aboda@apache.org>

This closes #823

dtrodrigues/nifi-minifi-cpp,jdye64/nifi-minifi-cpp,achristianson/nifi-minifi-cpp,jdye64/nifi-minifi-cpp,dtrodrigues/nifi-minifi-cpp,jdye64/nifi-minifi-cpp,achristianson/nifi-minifi-cpp,jdye64/nifi-minifi-cpp,achristianson/nifi-minifi-cpp,jdye64/nifi-minifi-cpp,achristianson/nifi-minifi-cpp,dtrodrigues/nifi-minifi-cpp,dtrodrigues/nifi-minifi-cpp,dtrodrigues/nifi-minifi-cpp