Update flux-sched to the latest KVS interface

[SteVwonder]

Looks like parts of flux-sched (at minimum the simulator) were still using the deprecated json-c KVS interface. flux-framework/flux-core#1100 replaces that with a jansson-based interface.

make[3]: Entering directory `/home/travis/build/flux-framework/flux-sched/flux-sched-0.3.0-45-gf5a7bcb/_build/sub/simulator'
  CC       libflux_sim_la-simulator.lo
../../../simulator/simulator.c: In function ‘pull_job_from_kvs’:
../../../simulator/simulator.c:209:5: error: implicit declaration of function ‘kvsdir_get_string’ [-Werror=implicit-function-declaration]
../../../simulator/simulator.c:218:5: error: implicit declaration of function ‘kvsdir_get_double’ [-Werror=implicit-function-declaration]
../../../simulator/simulator.c:227:5: error: implicit declaration of function ‘kvsdir_get_int’ [-Werror=implicit-function-declaration]
../../../simulator/simulator.c:233:5: error: implicit declaration of function ‘kvsdir_get_int64’ [-Werror=implicit-function-declaration]
cc1: all warnings being treated as errors

[garlick]

Sorry about that! Will get a PR cooked up ASAP.