Modify IME interface to use LS2 handle instead of mainloop

Note: This requires matching change in luna-sysmgr and luna-webkit-api

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

Change-Id: Id224bca9b0ad912700c293728509cee8d0db7e8b