[patch] support multiple authz-bypass URLs

[WindzCUHK]

add bypass URL path for supporting PCF GSLB health check

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other merged PR will be release tgt:

1. memory leak bugfix unclosed error channel on http handler #39 (released in [patch] add go binary version during build time #43)
2. [patch] fix lint #36 (next time)

[codecov-io]

Codecov Report

Merging #41 into master will increase coverage by 0.67%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master      #41      +/-   ##
==========================================
+ Coverage   85.56%   86.24%   +0.67%     
==========================================
  Files          14       14              
  Lines         589      589              
==========================================
+ Hits          504      508       +4     
+ Misses         75       71       -4     
  Partials       10       10

Impacted Files	Coverage Δ
config/config.go	100% <ø> (ø)	⬆️
main.go	46.05% <0%> (+2.3%)	⬆️
handler/transport.go	100% <100%> (ø)	⬆️

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[WindzCUHK]

authorization-proxy/handler/transport.go

Line 43 in 967110a

if err := glg.Debug("Authorization checking skipped on: " + r.URL.Path); err != nil {

Not sure the level should be Debug or Warn. Discuss later.
use Info

[kevindiu]

Please update the example file and corresponding test case here
example_config.yaml

[WindzCUHK]

Please update the example file and corresponding test case here
example_config.yaml

updated in 393a7d0

[kevindiu]

LGTM