Possibility to administer system users from within the CMS

Currently setting a (non-plain text) password for a system user is quite cumbersome.

• Login to console
• Set hipposys:system to false
• Write changes to repository
• Login to CMS
• Change the password
• Login to console
• Set hipposys:system to true
• Remove hipposys:passwordlastmodified property (See: REPO-600)
• Write changes to repository

It would be a good improvement to allow system users to be administered from within the CMS, possibly (preferably) with a "password never expires" checkbox. Note that these users should not be mixed in with the regular users to prevent over zealous admins from removing these "unknown" users. It should be clear in the interface that they're a separate category of users.

A quick fix would be to allow generating hashed passwords from the console.