Catch all Exceptions if guest crashed and fix command for tty1 process c...

    1. Move test steps into try..finally block, so the env can restore in
    any reason fail.
    2. When crash guest via session command, it may raise 2 type Exceptions,
    so catch them all to pass this step.
    3. If the guest started with X window, the old grep keyword can not find
    the tty1 process, so just use 'tty1' keyword for the checking.

Signed-off-by: Yanbing Du <ydu@redhat.com>
Shouldn't status of "ps aux|grep tty1" always be 0?
```
[root@domain virt]# ps aux|grep tty1sdfrt
root     13126  0.0  0.0 112664   936 pts/0    S+   14:22   0:00 grep --color=auto tty1sdfrt
[root@domain virt]# echo $?
0
```