Added a step to the flash upload process in the Files section to do a
preflight check to see if there are any duplicate filenames. If there are, the
user gets the option to either rename the new files, or overwrite the existing
ones. (Overwrite means deleting them - we already have code that will redirect
to new files with the same name as deleted files if they're linked directly by
id.)
Change-Id: I926631aadcebec3cae1607f818044f7cd4b74cea
Reviewed-on: https://gerrit.instructure.com/5091
Tested-by: Hudson <hudson@instructure.com>
Reviewed-by: Brian Palmer <brianp@instructure.com>
54bab9db59