Added TODO to remove references to ByteBuffer.array() without
checking whether the ByteBuffer does have a backing array.
Clearing the buffer in case of parser errors that lead to a
connection failure.
Implemented dispatch to the application using an ExecutionStrategy.

Now instead of having the channel to dispatch when it detects that it
has to call the application (upon receiving a HEADERS frame, or upon
a push "fake" request), now the whole mechanism is controlled by an
ExecutionStrategy.
Switched ExecutionStrategy to EWYK.
Temporarily commented out non-compiling code.
Code cleanups.
Cleaned up ExecutionStrategy by adding javadocs, removing methods not
used and renaming classes and methods to better names.