jsc,job,wreck: change key from lwj to jobid for consistency

[SteVwonder]

fixes: #1408

[coveralls]

Coverage decreased (-0.003%) to 78.885% when pulling 2e24286 on SteVwonder:fix1408 into 4a51fe1 on flux-framework:master.

[codecov-io]

Codecov Report

Merging #1409 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1409      +/-   ##
==========================================
- Coverage   78.58%   78.57%   -0.01%     
==========================================
  Files         163      163              
  Lines       29995    29995              
==========================================
- Hits        23571    23570       -1     
- Misses       6424     6425       +1

Impacted Files	Coverage Δ
src/modules/wreck/wrexecd.c	75.77% <ø> (ø)	⬆️
src/modules/wreck/job.c	72.47% <ø> (ø)	⬆️
src/common/libjsc/jstatctl.c	74.89% <100%> (ø)	⬆️
src/broker/modservice.c	79.61% <0%> (-0.98%)	⬇️
src/broker/overlay.c	74.14% <0%> (-0.63%)	⬇️
src/common/libflux/handle.c	83.66% <0%> (-0.5%)	⬇️
src/common/libkvs/kvs_watch.c	90.98% <0%> (-0.43%)	⬇️
src/common/libflux/message.c	81.48% <0%> (ø)	⬆️
src/cmd/flux-module.c	85.36% <0%> (+0.3%)	⬆️
src/common/libflux/mrpc.c	86.66% <0%> (+1.17%)	⬆️
... and 1 more

[garlick]

Thanks! Needs a rebase.

Does sched need to be updated to match this or is this change contained in core?

[SteVwonder]

This change is contained with core. Rebase coming up!

[grondo]

Thanks for taking care of this @SteVwonder