android/A2DP: Change to connected state when a transport open

This changes the connected state to be only sent once a transport is
open, before this was done right after the signalling was connected but
this reflect in the audio HAL side attempting to open a stream while
with possible no transport available.
android/A2DP: Fix selecting invalid bitpool range for SBC

For SBC bitpool range may not strictly match with presets so it needs to
be adjusted to fit within remote capabilities otherwise the remote device
may reject the configuration.
android/A2DP: Send stream fd in open stream response

This adds support of sending stream fd within open stream response.
android/A2DP: Add timeout to setup stream if remote becomes idle

If remote initiate the connection but do not setup any stream take over
the role and initiate the stream setup procedure.
android/hal-audio: Add audio_ipc_cmd

Add function to handle send/receive on audio_sk.
android/hal-audio: Add support to register audio endpoints

This patch adds support to register audio enpoints via Audio IPC.
Endpoints are registered based on predefined codecs table and for
each defined codec one endpoint is registered. By default, only
SBC will be supported.
android/hal-audio: Add support to unregister audio endpoints
android/hal-audio: Add support to open output stream

This patch adds support to open output stream via Audio IPC.
Since only SBC is supported, we always try to open stream for first
endpoint only which is enough.
android/hal-audio: Add support to close output stream
android/hal-audio: Add support to resume output stream

This patch adds support to resume output stream via Audio IPC.
Stream is automatically resumed on first write when stream is in
standby state.
android/hal-audio: Add support to suspend output stream

This patch adds support to suspend output stream via Audio IPC.
>From HAL perspective stream can be either in standby or suspended -
the former is default one and can be auto-resumed on write while the
latter cannot be resumed only after explicitly going into standby
on audio code request.
android/hal-audio: Handle audio preset from stream

This patch adds handling of audio preset received after stream is
opened. Preset is used to initialize codec and then to set input
configuration so audio subsystem can write data in a format that
codec can handle later.
android/hal-audio: Fix module loading
android/hal-audio: Fix AudioFlinger crash

We need to return some valid values for buffer size and latency so
AudioFlinger does not crash. For now just use some dummy values until
codec implementation is in place.
android/hal-audio: Implement set_parameters for device
android/bluetooth: Fix discovering new devices

Device found events should be send also for known devices if this is
new discovery session. Otherwise Android will ignore those devices.
android/a2dp: Fix typo in condition
[travis-ci] Add configuration file
[travis-ci] FIXUP: .travis.yml updates
android: Fix GNU old-style struct field designator

This gives a warning on clang, that turns into an error due to -Werror.