Stop doing circular imports in process.check_output

ovirt.node.utils.system requires ovirt.node.utils.process.
Circular imports make process unusable from a python shell.
Use try/except to work around missing check_output instead.

Change-Id: I78891bc3e1dffb6fba320f3bb8b982f2fca75049
Signed-off-by: Ryan Barry <rbarry@redhat.com>
performance_page.py: Drop "Reset" button

Previously "Reset" button wasn't necessary for this
page,need to drop it.
Also drop "Reset" button from keyboard_page;
drop "Reset" and "Save" button from diagnostics_page

Change-Id: I9870e17a098de4045fbdb75c8b02e5cc0f594816
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=978821
Signed-off-by: hadong <hadong0720@gmail.com>