feat: change json lib to jsoniter

[appleboy]

A high-performance 100% compatible drop-in replacement of "encoding/json"

https://github.com/json-iterator/go

cc @javierprovecho @tboerger

Signed-off-by: Bo-Yi Wu appleboy.tw@gmail.com

[javierprovecho]

@appleboy test failed:

• TestContextRenderIndentedJSON

=== RUN   TestContextRenderIndentedJSON
--- FAIL: TestContextRenderIndentedJSON (0.00s)
	Error Trace:	context_test.go:585
	Error:		Not equal: 
			expected: "{\n    \"foo\":\"bar\",\n    \"bar\":\"foo\",\n    \"nested\":{\n        \"foo\":\"bar\"\n    }\n}"
			received: "{\n    \"bar\": \"foo\",\n    \"foo\": \"bar\",\n    \"nested\": {\n        \"foo\": \"bar\"\n    }\n}"

• TestErrorSlice

=== RUN   TestErrorSlice
--- FAIL: TestErrorSlice (0.00s)
	Error Trace:	errors_test.go:94
	Error:		Not equal: 
			expected: "[{\"error\":\"first\"},{\"meta\":\"some data\",\"error\":\"second\"},{\"status\":\"400\",\"error\":\"third\"}]"
			received: "[{\"error\":\"first\"},{\"error\":\"second\",\"meta\":\"some data\"},{\"error\":\"third\",\"status\":\"400\"}]"
	

Both of them fail because json-ite sort the order of keys.

[appleboy]

@javierprovecho I already fixed it this commit 08338ef

[javierprovecho]

@appleboy it will keep failing, the tests here are trivial, json-ite outputs the json without ordering

[codecov]

Codecov Report

Merging #990 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #990   +/-   ##
=======================================
  Coverage   96.52%   96.52%           
=======================================
  Files          16       16           
  Lines        1412     1412           
=======================================
  Hits         1363     1363           
  Misses         39       39           
  Partials       10       10

Impacted Files	Coverage Δ
errors.go	100% <ø> (ø)	⬆️

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[appleboy]

@javierprovecho Yes. maybe we need open the issue to https://github.com/json-iterator/go

[javierprovecho]

http://godoc.org/github.com/json-iterator/go#pkg-variables

[codedance]

jsoniter also does not seem to work on Google App Engine (use of unsafe). One option may be to enable/disable this via build tags.