Plug in the ErrorHandlers for JSON/color compatibility of http lib logging

[ldemailly]

Fixes #802

Through support from fortio.org/log@1.10.0 (scli 1.11.0)
ie fortio/log#44

See manual test in fortio/proxy#145

[codecov]

Codecov Report

Patch coverage: 92.4% and project coverage change: -1.1% ⚠️

Comparison is base (abdbd19) 89.7% compared to head (057e56b) 88.5%.
Report is 7 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #812     +/-   ##
========================================
- Coverage    89.7%   88.5%   -1.1%     
========================================
  Files          17      17             
  Lines        4141    4983    +842     
========================================
+ Hits         3713    4412    +699     
- Misses        279     422    +143     
  Partials      149     149             

Files Changed	Coverage Δ
fnet/network.go	89.5% <75.0%> (-0.9%)	⬇️
rapi/restHandler.go	86.4% <87.0%> (-0.8%)	⬇️
periodic/periodic.go	92.7% <92.0%> (-1.1%)	⬇️
fhttp/http_server.go	81.7% <100.0%> (-4.2%)	⬇️
fhttp/httprunner.go	91.8% <100.0%> (-0.3%)	⬇️

... and 11 files with indirect coverage changes

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