Allow to override default retry wait times for Client

[bak1an]

This resolves #64

Changes made here:

• Changing retry wait time options to have time.Duration type instead of of int holding milliseconds.

• Adding RetryWaitTime and RetryMaxWaitTime fields to Client along with chaining setters.

• A condition to make sure Backoff always sleeps at least WaitTime duration. Before this change it could sleep less than this due to jitter we have there. Especially before the very first retry, the sleep duration was always somewhere between WaitTime / 2 and WaitTime.

• Test to make sure overridden wait times are actually used.

[codecov-io]

Codecov Report

Merging #66 into master will increase coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #66      +/-   ##
==========================================
+ Coverage   96.74%   96.78%   +0.03%     
==========================================
  Files          11       11              
  Lines         892      902      +10     
==========================================
+ Hits          863      873      +10     
  Misses         15       15              
  Partials       14       14

Impacted Files	Coverage Δ
client.go	95.69% <100%> (+0.09%)	⬆️
default.go	100% <100%> (ø)	⬆️
retry.go	100% <100%> (ø)	⬆️
request.go	100% <100%> (ø)	⬆️

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[jeevatkm]

Thank you for effort and time. Implementation looks perfect.

I think we have to add info about these defaults in godoc or Readme.md. What do you think?

defaultWaitTime    = time.Duration(100) * time.Millisecond
defaultMaxWaitTime = time.Duration(2000) * time.Millisecond

[bak1an]

@jeevatkm Makes sense.

I'll add some info on retries to readme.

[jeevatkm]

Thank you @bak1an.

[jeevatkm]

@bak1an Shall I go ahead and merge this PR or wait for your readme changes? Please let me know.

[bak1an]

@jeevatkm

Sorry for the delay,

Added some retry usage doc and mentioned delay defaults in doc.

[jeevatkm]

Thank you @bak1an, I appreciate it.