[bluetooth] udev rules and system service for bluetooth initialization

- Run hciattach when UART tty becomes available so that hci0 can be
  accessed

- Ensure /dev/rfcomm devices have proper permissions to enable sync
  over BT
Merge pull request #47 from hmallat/lge-hammerhead-hciattach

[bluetooth] udev rules and system service for bluetooth initialization
[configs] Add multimedia keys and a US keyboard layout

To enable Bluetooth headset multimedia keys (play, pause, etc.) the
corresponding keycodes need to be defined. Brought in adenexter's
changes to Jolla keymap config.

To enable Bluetooth keyboards brought in mikkoh's US keymap from Jolla.
Merge pull request #48 from hmallat/keymap-update

[configs] Add multimedia keys and a US keyboard layout
[hammerhead][patterns] Add mce-plugin-libhybris to get working notification LEDs

Signed-off-by: Matti Kosola <matti.kosola@jolla.com>