Multi-user implementation feature

Multi-user implementation feature

- Desactivate preload features
- Create am_agent process
- Remove old launchpad daemon
- Make am_agent discuss with amd process to launch an app
- Add Crosswalk Launchpad capabilities
- renamed am_agent to am_session_agent; fix segfault in amd_session_agent after first app launch
- cleanup agent code, added uid in amd request to agent
- Fix build with Cosswalk and add Dbus call
- fix build; added specific dlog tag for agent
- fix caller_uid check in agent
- Use DBUS SESSION bus instead of DBUS SYSTEM bus
- amd_session_agent now sends an APP_DEAD_SIGNAL request to amd daemon to signal the end of an app
- Fix Error Management
- amd: check that sender of APP_DEAD_SIGNAL is /usr/bin/amd_session_agent
- Add systemd service
- Add User Management for get applications ,Remove DBUS launch mechanism
- get uid for multiuser support

more info : https://wiki.tizen.org/wiki/Multi-user_Architecture

Change-Id: Iee37e603cb366d94bcc945df7edf3c3817fdee82
Signed-off-by: Baptiste DURAND <baptiste.durand@open.eurogiciel.org>
Signed-off-by: Stephane Desneux <stephane.desneux@open.eurogiciel.org>
Signed-off-by: Sabera Djelti (sdi2) <sabera.djelti@open.eurogiciel.org>
Signed-off-by: Jean-Benoit MARTIN <jean-benoit.martin@open.eurogiciel.org>