Mac下启动出错

#### Which platform are you running AnyProxy
Mac
#### The version of the AnyProxy
4.0 beta

#### Your expected behavior of AnyProxy
无法启动anyproxy

#### The actual behavior of AnyProxy

#### The log of the error
/usr/local/node-v4.6.0/lib/node_modules/anyproxy/proxy.js:253
for (const [key, conn] of this.requestHandler.conns) {
^

SyntaxError: Unexpected token [
at exports.runInThisContext (vm.js:53:16)
at Module._compile (module.js:373:25)
at Object.Module._extensions..js (module.js:416:10)
at Module.load (module.js:343:32)
at Function.Module._load (module.js:300:12)
at Module.require (module.js:353:17)
at require (internal/module.js:12:17)
at Object. (/usr/local/node-v4.6.0/lib/node_modules/anyproxy/bin/anyproxy:34:20)
at Module._compile (module.js:409:26)
at Object.Module._extensions..js (module.js:416:10)

Start by reproducing the startup failure on macOS with Node.js v4.6.0, then inspect proxy.js around line 253, where the reported syntax error occurs. Compare that syntax with the runtime's supported JavaScript features and verify that AnyProxy starts successfully after the issue is addressed.

Written by the indexing model from the issue text.