fix path for jar, make sed actually work on OSX

Author: Nick Lanham <nick@afternight.org>

Closes #264 from nicklan/make-distribution-fixes and squashes the following commits:

172b981 [Nick Lanham] fix path for jar, make sed actually work on OSX

(cherry picked from commit 75d46be5d61fb92a6db2efb9e3a690716ef521d3)
Signed-off-by: Matei Zaharia <matei@databricks.com>