Less verbosity
Add retry count to jar fetching

Basically, I tested this by running this:

    rm -r ~/.m2/repository/com/spotify/bs/pipeline-echonest/ ; each 'greaserun --runner shell com.spotify.bs:pipeline-echonest:RELEASE -- echo hi 2>&1 | tee output-$x &' 1 2

And this patch fixed the problem.

https://jira.spotify.net/browse/DATAEX-249
Merge pull request #27 from Tarrasch/fix-robust-jar-download

Fix robust jar download