README: fix command for debugging Gulp on Windows

In most cases, this command just can be copied and run,
and it will work without modifications.

Close #467
Console serializing and caching logic moved to InjectorServer
Added HeapProfiler._lookupHeapObjectId

Closes #473
Modified DebuggerAgent.getFunctionDetails

DebuggerAgent.getFunctionDetails modified to correctly lookup
heap snapshot and console message functions.

Closes #474