Not support for ES6 constructor method in sort-comp rule

[tangrui]

The new React 0.13.x introduces ES6 features, which allows to write ES6 classes.

class MyComp extends React.Component {
  constructor() { ... }
  render() { ... }
}

We should always put constructor method at the very beginning of the class, but in this way, eslint will complain: constructor must be placed after render. If I place the "constructor" in the order options to adjust the rule, eslint will throw error:

/Users/tangrui/.nvm/v0.10.36/lib/node_modules/eslint-plugin-react/lib/rules/sort-comp.js:105
      isRegExp = methodsOrder[i].match(regExpRegExp);
                                 ^
TypeError: Object function Object() { [native code] } has no method 'match'
    at getRefPropIndexes (/Users/tangrui/.nvm/v0.10.36/lib/node_modules/eslint-plugin-react/lib/rules/sort-comp.js:105:34)
    at comparePropsOrder (/Users/tangrui/.nvm/v0.10.36/lib/node_modules/eslint-plugin-react/lib/rules/sort-comp.js:258:23)
    at checkPropsOrder (/Users/tangrui/.nvm/v0.10.36/lib/node_modules/eslint-plugin-react/lib/rules/sort-comp.js:322:17)
    at EventEmitter.Program:exit (/Users/tangrui/.nvm/v0.10.36/lib/node_modules/eslint-plugin-react/lib/rules/sort-comp.js:351:9)
    at EventEmitter.emit (events.js:117:20)
    at Controller.controller.traverse.leave (/Users/tangrui/.nvm/v0.10.36/lib/node_modules/eslint/lib/eslint.js:733:25)
    at Controller.__execute (/Users/tangrui/.nvm/v0.10.36/lib/node_modules/eslint/node_modules/estraverse/estraverse.js:393:31)
    at Controller.traverse (/Users/tangrui/.nvm/v0.10.36/lib/node_modules/eslint/node_modules/estraverse/estraverse.js:481:28)
    at EventEmitter.module.exports.api.verify (/Users/tangrui/.nvm/v0.10.36/lib/node_modules/eslint/lib/eslint.js:718:24)
    at processFile (/Users/tangrui/.nvm/v0.10.36/lib/node_modules/eslint/lib/cli-engine.js:197:27)