4.0.0-alpha.1

This is a pre-release version of SwiftyJSON 4.0.0.

Changes:

• (1c5e902 @MikotoZero) Simplify initialize methods invocation.
• (a76d81d @craiggrummitt) Fix "double t" spelling mistake, writtingOptionsKeys now is writingOptionsKeys.
• (f9afe96 @wongzigii) SwiftyJSON now use throws for error handling
  init(data, options opt, error) now is init(data, options opt) throws.
• (083c6d7 @wongzigii) Use Swift.Error type instead of NSError, now JSON's error is SwiftyJSONError type.

Improvements:

• (619fba2 @wongzigii) SwiftLint compatible.
• (1d64b89 @wongzigii) Add GitHub issue and pull request template.
• (d932f64 @matthew-an) Fix a potential crash issue by checking whether index is out of json array’s bound.
• (e4b2644 @JeffGuKang @Humoud) Documentation improvement and source code gardening.
• (#887 @Taillook, @hitendradeveloper, @Harshit31) Add "yes" and "1" to string.boolValue array

Thank @JackSteven, @mictab, @neoneye, @Tawfikk and others who helped review the pull requests and contribute to the documentations. 🎉 🎉