Profiler API

Realisation of Profiler agent.
Implemented:
Profiler.enable
Profiler.disable
Profiler.star
Profiler.stop
Profiler.getProfileHeaders
Profiler.getCPUProfile
Profiler.removeProfile
Profiler.clearProfiles
Profiler.addProfileHeader
Profiler.setRecordingProfile
Profiler.resetProfiles

Related: #185
This is rather ugly. How about this?

```js
var frontendClient = new EventEmitter();
frontendClient.sendEvent = function(event, message) {
  this.emit(event, message);
};
```