[#6638] Added importer for exported Allura JSON

Signed-off-by: Cory Johns <cjohns@slashdotmedia.com>
[#6638] Added importer for exported Allura JSON

Signed-off-by: Cory Johns <cjohns@slashdotmedia.com>
Merge branch 'cj/6638' of https://git-wip-us.apache.org/repos/asf/incubator-allura into cj/6638
[#6638] Remove old import_id before creating app

Signed-off-by: Tim Van Steenburgh <tvansteenburgh@gmail.com>