Heapprofiler API

Not finished (needs HeapGraph, GarbageCollector)
Implemented:
HeapProfiler.getProfileHeaders
HeapProfiler.startTrackingHeapObjects
HeapProfiler.stopTrackingHeapObjects
HeapProfiler.getHeapSnapshot
HeapProfiler.removeProfile
HeapProfiler.clearProfiles
HeapProfiler.takeHeapSnapshot
HeapProfiler.addProfileHeader
HeapProfiler.addHeapSnapshotChunk
HeapProfiler.finishHeapSnapshot
HeapProfiler.reportHeapSnapshotProgress
HeapProfiler.lastSeenObjectId
HeapProfiler.heapStatsUpdate

Related: #185


I think this comment is copy pasted from Profiler API.

I'll also check in this commit problems similar to Profiler API. (Now I work on config issues, and will fix this at thursday)