Added build target for httptest in build.xml.
Added build target for httptest in build.xml.

sguazt/rain-workload-toolkit,yungsters/rain-workload-toolkit,marmbrus/rain-workload-toolkit,yungsters/rain-workload-toolkit,yungsters/rain-workload-toolkit,mrcaps/rain-workload-toolkit,mrcaps/rain-workload-toolkit,marmbrus/rain-workload-toolkit,sguazt/rain-workload-toolkit,sguazt/rain-workload-toolkit,mrcaps/rain-workload-toolkit,marmbrus/rain-workload-toolkit