[ISSUE #288] Add SetLogger method

[wenfengwang]

• add SetLogger method for the user to specify a customized logger
• add Code Coverage label in README.md

[codecov-io]

Codecov Report

Merging #290 into native will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           native     #290   +/-   ##
=======================================
  Coverage   26.15%   26.15%           
=======================================
  Files          46       46           
  Lines        5058     5058           
=======================================
  Hits         1323     1323           
  Misses       3558     3558           
  Partials      177      177

Impacted Files	Coverage Δ
internal/route.go	4.76% <0%> (ø)	⬆️

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