Email servers connection password should be encrypted

Passwords stored in MailArchiveCode.ServerClass objects should be stored encrypted.

Possibilities:
[1] http://xwiki.org/xwiki/bin/view/ReleaseNotes/ReleaseNotesXWiki541#HNewextensiblecryptographicAPIs
[2] http://extensions.xwiki.org/xwiki/bin/view/Extension/Encryption+Application

This is for crypt/decrypt password string, but encryption must occur when XObject is saved or updated. Maybe could be done with Events (ie, update object before it is saved).