Bug fix: specify the class attribute when change pool state dot.

After we list the storage pools, it will change other element with the
same class attribute in other page.

Signed-off-by: ShaoHe Feng <shaohef@linux.vnet.ibm.com>
Signed-off-by: Hongliang Wang <hlwang@linux.vnet.ibm.com>
but fix: show the content of combobox and filterselect in storage add page

On firefox 27, the content of combobox and filterselect will hide.

a similar problem on issue.
https://github.com/kimchi-project/kimchi/issues/335

Signed-off-by: ShaoHe Feng <shaohef@linux.vnet.ibm.com>
Signed-off-by: Hongliang Wang <hlwang@linux.vnet.ibm.com>