droplet: merge sproxyd_backend branch into trunk

svn merge -c32961,32963,32964,32968,32969,32970,32976,32979,
            32993,32994,32999,33006,33007,33008,33013,33029,
            33030,33031,33032,33040,33041,33042,33043,33048,
            33243,33348,33350,33352,33375,33376,33792,33818,
            33819,33848,33849,34477,34478,34497,34776,34837,
            34958,34960 ../branches/sproxyd_backend/

Make some adjustments in different Makefile.am and configure.ac
make the whole stuff build properly