Wiab profiling.

The basis of profiling code was taken from the Splash project (https://code.google.com/p/google-wave-splash/).

Features appended to Splash profiling code:
 1. Current authentification session context.
 2. Cross-thread profiling (one request is executed in several threads simultaneously).
 3. Client-side profiling.
 4. GWT profiling.
 5. Loading of scope through static object (instead of custom Guice scope).
 6. Profiling popup dialog.

Server code changes:
 1. Used only own-designed RequestScopeExecutor and ScheduledRequestScopeExecutor, transferring profiling context to the executed task.
 2. Profiling context is set in following places:
  - RequestScopeFilter - for Servlet requests
  - WebSocketChannel - for WebSocket requests

Client code changes:
 1. Added GWT profiling:
  - Added handling of event.__gwtStatsEvent
  - Added own listener, as defined in https://code.google.com/p/gwt-debug-panel/wiki/GettingStarted.
 2. Used only own-designed custom executor BrowserBackedScheduler, transferring profiling context to the executed task.
 3. Profiling context is set in following places:
  - Keyboard events - FocusManager.dispatch
  - Mouse events - EventDispatcherPanel.ChangeHandlers.dispatch
  - Client RPC requests - RemoteWaveViewService

Statistics recorded on the server:
 1. Accumulated statistics for task calls for current session and whole program:
  - Methods of objects, created by Guice Inject, and annotated as @Timed.
  - Code from Timing.start() or Timing.startRequest() to Timer.stop().
 2. Statistics for last 100 requests with execution tree for current session and whole program:
  - Code from Timing.startRequest() to Timer.stop().
 3. Statistics for static fields, annotated as @Stat.

Statistics recorded on the client:
 1. Accumulated statistics for task calls:
  - Code from Timing.start() or Timing.startRequest() to Timer.stop().
 2. Statistics for last 100 requests with execution tree:
  - Code from Timing.startRequest() to Timer.stop().

How to display statistics:
 1. In order to show profiling dialog in the client, press and release one-by-one Ctrl, Alt and Ctrl keys.
 2. To show only server statistics go to URL <wave_server_url>/speedz.