improve get transport folder function

It was looking for a folder by PidTagDisplayName so if we changed the
language, brokeness.

We can accomplished the same filtering by SystemIdx, because is unique
change get_new_folderID calls to add username as parameter

instead of taking the one of the current session
change openchangedb_create_folder calls, don't use emsmdbp_context username
Merge pull request #29 from Zentyal/jgarcia/be-able-to-send-emails-with-i18n-mailbox

Send emails with mailbox != english
Merge pull request #30 from Zentyal/jgarcia/fix-initial-provision-mailbox-with-different-user

Fix mailbox provision when previously logged as different user
Merge branch 'master' into precise-cloud