i18n mailboxes

We have 2 mysql tables with folder's display names translated, one row per locale (it could be either full locale 'en_UK' or only 'en'). When mailbox is provisioned the names will be set as usual (PidTagDisplayName property), and every time the locale of the mailbox changes, they will be set again.

It also works for current openchangedb ldb implementation because we have hardcoded names on code (right now only english and spanish, we could add more), those names are used in case openchangedb backend don't success on trying to fetch folder's names (which will be always in ldb implementation)