feat: added display-errors & display-sections option

[Gcaufy]

Checklist

• npm test passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Description of change

Similar to this PR: #30

1. Added displayErrors option

I added a displayErrors option, (like php display_errors). Because we can not say if env !== 'local' or env !== 'unittest' then env = 'prod', there are may test/uat...environments that we still need to show error stacks. I added this option so that we don't need to use env variable to see display errors or not. That's user behaviors. if they need to display errors in different env, then they can easily handle it in config files, like:

{
  displayErrors: process.env.NODE_ENV !== 'production'
}

or

{
  displayErrors (app) => app.env !== 'prod'
}

2. Added displaySections option

For some sections in error page, they are highly sensitive, like the appInfo section, or cookie section. Normally it contains the server side database password or user sensitive information. If we want to display errors in test/uat environment. then we should not to display those information to everybody. So I added this option. so that user can customize what section they want to show in the error pages

[codecov]

Codecov Report

Merging #33 into master will increase coverage by 0.21%.
The diff coverage is 96.15%.

@@            Coverage Diff            @@
##           master     #33      +/-   ##
=========================================
+ Coverage   96.98%   97.2%   +0.21%     
=========================================
  Files           5       5              
  Lines         166     179      +13     
=========================================
+ Hits          161     174      +13     
  Misses          5       5

Impacted Files	Coverage Δ
config/config.default.js	100% <ø> (ø)	⬆️
app.js	97.18% <100%> (+0.12%)	⬆️
lib/error_view.js	96.59% <95.45%> (+0.43%)	⬆️

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[hyj1991]

+1

[hyj1991]

这个 PR 的逻辑没问题，而且自定义看起来也是一个需求的点，但是形式上是使用允许自定义 isProd 函数还是额外增加 displayErrors 的配置需要从设计上考虑下，cc @atian25

Reference：#30