Move the io_handler code out of shill_event

Create io_handler.h and glib_io_handler.{cc,h} to contain
all the io hander stuff.  The code is ostensibly the same.

BUG=chromium-os:15803
TEST=Rerun unit tests

Change-Id: I3e37ac643c5c4449ae0db8b9a5f02225e8cd2aec
Reviewed-on: http://gerrit.chromium.org/gerrit/1630
Tested-by: Paul Stewart <pstew@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
5 files changed