add support for tar and tar.gz archives in content migrations

also add limits for byte size and file count to prevent
zip/tar "bombs"

test plan:
 * import the package referenced in the ticket
 * should import successfully

 * content migration regressions

closes #CNVS-14303 #CNVS-14428

Change-Id: Ia424b5260e34f35b62ca47f7aafa77118c4f5b5b
Reviewed-on: https://gerrit.instructure.com/37881
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Trevor deHaan <tdehaan@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>