Add USE_KEY_FILTER and USE_MOUSE_FILTER options

Re-applying the commit by Eric Blade <eric.blade@palm.com>
made for luna-sysmgr to here as well with modifications.

- USE_KEY_FILTER enables automatic translation of Home, End, Pause,
  Escape to equivalent CoreNavi events or Pause => Key_Power
- USE_MOUSE_FILTER enables some optional mouse input processing

Open-webOS-DCO-1.0-Signed-off-by: Jukka Honkela <jukka.honkela@palm.com>

Change-Id: I0a044cf204d2a91c5a2db2087c5e36e4480ff152
Use pkg config to find sysmgr-ipc headers

Open-webOS-DCO-1.0-Signed-off-by: Mikko Levonmaa <mikko.levonmaa@palm.com>

Change-Id: I93ae8536c7cf11a81be4efb5d6b1be2470faec99
Update build instructions in README file

Open-webOS-DCO-1.0-Signed-off-by: Roger Stringer <roger.stringer@palm.com>

Change-Id: Ie2593605d6ab7078ddea7b1064e1e8fcee6a114e
Fix Qt5 migration of HostArmQtKeyFilter

Change the contant value of power key to prevent a compile error when enabling USE_KEY_FILTER

Open-webOS-DCO-1.0-Signed-off-by: Kwangsub Kim <kwangsub.kim@palm.com>

Change-Id: I2e0ca9dafc3a3952ac0140c13360c4761be34469
Merge git://github.com/openwebos/luna-sysmgr-common into halfhalo/slate