Org directory to Dropbox to be used with MobileOrg

MovileOrg is the Android app for org-mode, it will be nice to access org
notes from Dropbox and even with the Dropbox Android app, but it can be
used also with MobileOrg, Dropbox is one of the methods to use
MobileOrg, and sync all org notes.

http://orgmode.org/manual/Setting-up-the-staging-area.html#Setting-up-the-staging-area