Extend JSC to add R_lite support

[dongahn]

This PR supports the R_lite writer PR which I will post soon to flux-sched.

Also add some minor fixes along the way:

• Fix encoding errors for RDL query and update within JSC ([enhancement] Need to emit R_lite flux-sched#312 (comment))
• Remove trailing whitespace in flux-jstat command.
• Adjust an RDL test needed for the encoding fix.

Add a very simple R_lite test to a JSC test.

[coveralls]

Coverage decreased (-0.06%) to 78.973% when pulling 9a4ba90 on dongahn:R_lite_jsc into 86d5b32 on flux-framework:master.

[codecov-io]

Codecov Report

Merging #1485 into master will decrease coverage by 0.05%.
The diff coverage is 47.36%.

@@            Coverage Diff             @@
##           master    #1485      +/-   ##
==========================================
- Coverage   78.72%   78.66%   -0.06%     
==========================================
  Files         164      164              
  Lines       30358    30405      +47     
==========================================
+ Hits        23900    23919      +19     
- Misses       6458     6486      +28

Impacted Files	Coverage Δ
src/common/libjsc/jstatctl.c	72.35% <40.81%> (-1.92%)	⬇️
src/cmd/flux-jstat.c	85.84% <87.5%> (ø)	⬆️
src/common/libflux/response.c	83.73% <0%> (-0.82%)	⬇️
src/modules/kvs/kvs.c	65.87% <0%> (-0.17%)	⬇️
src/bindings/lua/flux-lua.c	81.58% <0%> (-0.09%)	⬇️
src/common/libflux/message.c	81.48% <0%> (+0.23%)	⬆️
src/broker/overlay.c	74.13% <0%> (+0.31%)	⬆️
src/common/libutil/base64.c	95.77% <0%> (+0.7%)	⬆️

[dongahn]

Just posted the corresponding flux-sched PR: flux-framework/flux-sched#321

[garlick]

@dongahn, this looks like it solves the problem, and I'm glad you added the test.

I think there are quite a few issues that shouldn't blow by without comment, such as

• logging within a library
• embedded synchronous RPCs
• use of json-c
• use of functions that assert on malloc failure

However, this code is consistent with hte rest of the library and I think we could merge it as is with the plan to create something new for the new execution system. Is that reasonable?

[dongahn]

That sounds reasonable to me. Thanks @garlick.