Fixes issue #1064 by switching to a named logger

[bdurrer]

What kind of change does this PR introduce?
bugfix

Did you add or update the examples/?
no

Summary
This solves issue #1064
So far, the client JS of webpack-dev-server used the root logger and also changed the configuration of the root logger. This results in webpack overwriting the application's logging configuration.
The PR switches to a named logger, as suggested in the issue description.

Does this PR introduce a breaking change?
I don't think it could break an app.

However, if an application uses loglevel and expects webpack-dev-server to configure the root logger, it might have an different log level than expected.
The solution for the app would be to call loglevel's setLevel or setDefaultLevel (which is how you should do it anyway).

[jsf-clabot]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #1070 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1070   +/-   ##
=======================================
  Coverage   73.17%   73.17%           
=======================================
  Files           5        5           
  Lines         451      451           
  Branches      143      143           
=======================================
  Hits          330      330           
  Misses        121      121

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[shellscape]

@bdurrer looks good. please sign the CLA (see first comment) and we can move forward

[bdurrer]

@shellscape
I did sign the CLA, but I used the wrong email. Adding the other email to the GitHub account did not help, nor can I change the js-cla data anymore after submitting 😒

[bdurrer]

Resetting and commiting the same thing again worked.

[shellscape]

ah perfect, thanks!