wreck: add support for a `no-filter-jobid` option

[SteVwonder]

Avoid removing "*_JOBID" variables from the job's environment when the no-filter-jobid option is provided to wreck. Useful when users are running jobs that leverage libyogrt and need SLURM_JOBID and the like to be passed through.

For more details, see: https://github.com/flux-framework/flux-core/issues/2358

[codecov-io]

Codecov Report

Merging #29 into master will increase coverage by <.01%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #29      +/-   ##
==========================================
+ Coverage   80.21%   80.22%   +<.01%     
==========================================
  Files         197      197              
  Lines       35430    35430              
==========================================
+ Hits        28421    28424       +3     
+ Misses       7009     7006       -3

Impacted Files	Coverage Δ
src/modules/kvs-watch/kvs-watch.c	78.88% <0%> (-0.89%)	:arrow_down:
src/cmd/flux-event.c	77.97% <0%> (-0.6%)	:arrow_down:
src/broker/modservice.c	80.76% <0%> (+0.96%)	:arrow_up:
src/modules/connector-local/local.c	74.81% <0%> (+1.03%)	:arrow_up:

[grondo]

Thanks! Will merge once travis passes.

[grondo]

Restarted a builder that hung during apt upgrade (I think). Same spot as in the other PR, hope Travis isn't having a bad day.

[SteVwonder]

Thanks @grondo!