CLOUDSTACK-7814: Fix default passphrase for keystores

In upgrade case, the db.properties file is not changed, but the following commit
would require passphrase for keystore in it, thus result in error(NPE in fact
due to there is no such properity).

commit 918c320438980f070150f872e3a3ba907572af83
Author: Upendra Moturi <upendra.moturi@sungard.com>
Date: Fri Jun 20 11:41:58 2014 +0530
CLOUDSTACK-6847.Link.java and console proxy files have hardcoded value

This commit fix it by put default value for passphrases, also set correct
passphrase if fail-safe keystore is used.