Get rid of glog.fatal

[leszko]

We should not use glog.fatal(), because its behavior changed in the glog library and now it prints the stack dump of each goroutine. This results in too many logs printed even if you enter a wrong parameter in your configuration.

[codecov]

Codecov Report

Merging #2900 (954e437) into master (366c2d6) will increase coverage by 0.02523%.
The diff coverage is 0.00000%.

@@                 Coverage Diff                 @@
##              master       #2900         +/-   ##
===================================================
+ Coverage   56.47192%   56.49715%   +0.02523%     
===================================================
  Files             89          89                 
  Lines          19461       19447         -14     
===================================================
- Hits           10990       10987          -3     
+ Misses          7863        7852         -11     
  Partials         608         608                 

Files	Coverage Δ
clog/clog.go	62.25166% <ø> (+2.37905%)	⬆️
cmd/livepeer_cli/wizard_stream.go	0.00000% <ø> (ø)
cmd/livepeer/livepeer.go	50.00000% <0.00000%> (ø)
monitor/census.go	63.30709% <0.00000%> (ø)
cmd/livepeer/starter/starter.go	4.73422% <0.00000%> (+0.02737%)	⬆️

... and 1 file with indirect coverage changes

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Files	Coverage Δ
clog/clog.go	62.25166% <ø> (+2.37905%)	⬆️
cmd/livepeer_cli/wizard_stream.go	0.00000% <ø> (ø)
cmd/livepeer/livepeer.go	50.00000% <0.00000%> (ø)
monitor/census.go	63.30709% <0.00000%> (ø)
cmd/livepeer/starter/starter.go	4.73422% <0.00000%> (+0.02737%)	⬆️

... and 1 file with indirect coverage changes