48848: ALF-18520: Mails subsystem fails with Nullpointer during initialization
If option is set to send test message on mail subsystem init then do it on behalf of System user.
During getFrom field calculation if there is no current user then send mail from default address
like it is System user. Case to unit test was added.
Reformatted MailActionExecuterTest
git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@48866 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261