libvirt.tests: Default to use unsafe for migration testcases.

If there is not 'cache=none' for vm disks, migration will be failed:
error: Unsafe migration: Migration may lead to data corruption if disks use cache != none
So for those cases that do not care about safe, we can pass --unsafe by default.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
migration.tests: Limit some tests to Linux only.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
timer_management: Deal with different date format.

Date&Time format of windows may be Week Month/Day/Year or
Year/Month/Day Week. Now dealing with it in different way.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
timer.windows: Fix test problems for Windows.

* Filter some testcases that need to change clocksource out
  for Windows.
* Fix parameter error: operation should be stress_type in
  configuration file.
* Windows OS use localtime as hardware time, while Unix is UTC.
  So they should have different checking way.
  TimeZone time in windows should compare with 'UTC time' on host
  for different clock type in XML.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
virsh.edit: New cases for editing memory value and memory unit

Signed-off-by: Yanbing Du <ydu@redhat.com>
avoid risk caused by using count() check user-define-value.

In some scripts,
we use count() to check if the value of self-variable,
needed by special circumstances, has been set or not.
But, it will bring some problem. for example,

 The self-variable declared at the corresponding config file.

 iface_name = "ENTER.BRIDGE.NAME"

 If the user just delete the prompt message and keep it "none".
 the following code will regard 'none' as a valid value without
 any error.

 iface_name = params.get("iface_name")
 if iface_name.count("ENTER"):
     raise error.TestNAError("Please input a existing bridge/ethernet name")

This patch fixes the problem.
libvirt.tests: Add tests for vcpu plug/unplug with different scenarios

Signed-off-by: Yanbing Du <ydu@redhat.com>
test.migrate_multi_vms: Check connectivity during migration.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
Merge pull request #332 from will-Do/vcpu

libvirt.tests: Add tests for vcpu plug/unplug with different scenarios
Merge pull request #386 from yumingfei/migration_unsafe_and_windows

tests.migration: Several enhancements.
Merge pull request #390 from PandaWei/default

avoid risk caused by using count() check user-define-value.
Merge pull request #381 from yumingfei/timer_win2012

timer_management: Deal with different date format for windows guest.
Merge pull request #361 from will-Do/edit_mem

virsh.edit: New cases for editing memory value and memory unit
Add graphics feature test.

Test of libvirt SPICE/VNC related features.

1) Block specified ports if required;
2) Setup SPICE TLS certification if required;
2) Setup VNC TLS certification if required;
3) Setup graphics tag in VM;
4) Try to start VM;
5) Parse and check result with expected.
6) Clean up environment.

Signed-off-by: Hao Liu <hliu@redhat.com>