misc: dropbox: add support for file events

This will allow drivers to add dropbox events with data containing the
path of a file which should be added to the dropbox.

Change-Id: I23757db8fda4d65019a97c83e4d8bb6fbfe27962
Signed-off-by: Patrick Auchter <wpa722@motorola.com>
Reviewed-on: http://gerrit.pcs.mot.com/617705
Tested-by: Jira Key <jirakey@motorola.com>
Reviewed-by: Jared Suttles <jsuttles@motorola.com>
Reviewed-by: Fred Fettinger <fettinge@motorola.com>
Reviewed-by: Stephen Rossbach <rossbach@motorola.com>
Submit-Approved: Jira Key <jirakey@motorola.com>
SLTApproved: Christopher Fries <c.fries@motorola.com>