Increase size of the the adb packets sent over the wire

The reason behing this change is to increase the adb push/pull speed
with reduceing the number of packets sent between the host and the
device because the communication is heavily bound by packet latency.

The change maintains two way compatibility in the communication
protocol with negotiating a packet size between the target and the
host with the CONNECT packets.

After this change the push/pull speeds improved significantly
(measured from Linux-x86_64 with 100MB of data):

           | Old push | Old pull || New push  | New pull  |
-----------------------------------------------------------
Hammerhead | 4.6 MB/s | 3.9 MB/s || 13.1 MB/s | 16.5 MB/s |
-----------------------------------------------------------
Volantis   | 6.0 MB/s | 6.2 MS/s || 25.9 MB/s | 29.0 MB/s |
-----------------------------------------------------------
Fugu       | 6.0 MB/s | 5.1 MB/s || 27.9 MB/s | 33.2 MB/s |
-----------------------------------------------------------

Change-Id: Id9625de31266e43394289e325c7e7e473379c5d8