Add a guard to ensure that macros and getters object are always initiated

Breaking Change

Renamed internal properties _macros and _getters to macros and getters and also Macroable will complain when these properties are not defined on the parent class. For example:

class Foo extends Macroable {}

new Foo() // throws error

class Foo extends Macroable {}
Foo.macros = {}
Foo.getters = {}

new Foo() // works fine

Commits

• docs(README): update badges url eb60941
• ci: remove travis,appveyor in favor of circleci 59c5d3f
• docs(REAMDE): update usage docs 1997389
• chore(package): remove unwanted dependencies 7c5eb1d
• refactor: raise exception when macros and getters are not initiated on class 66c046e
• chore: update dependencies a4c40b8

v3.0.0...v4.0.0