pass test in fedora 20

feature in fedora:
   only enable/disable and crashkernel configuration
   only support crashkernl="numberM" syntax

Signed-off-by: Arthur Zou <zzou@redhat.com>
pass tui test in fedora20

     feature: fedora support enable/disable and crashkerle=xxxM syntax
              redhat also support auto
     defect: both fedora and redhat can't restrict the range of
             crashkernel. This may cause system reserve too much or too
             little memory.

Signed-off-by: Arthur Zou <zzou@redhat.com>
Add reserve memory restriction for tui

If the reserved memory out of range, changing to default. For redhat
is auto, for fedora is the minimun memory needed by kdump.

Signed-off-by: Arthur Zou <zzou@redhat.com>