webadmin: Stay in the same tab if possible

Suggested behaviour for the system tree:
 - Dont change the selected main tab if the new tree item can show that tab

Example case:
Hosts tab is selected -> select spesific storage in system tree
old behaviour: switch to clusters tab
new behaviour: stay in hosts tab (because it is possible)

Change-Id: I2c27536ecb5ef9a8f48205c217fbdf295860e363
Signed-off-by: noam slomianko <nslomian@redhat.com>