SPARK-3745 - fix check-license to properly download and check jar

for details, see: https://issues.apache.org/jira/browse/SPARK-3745

Author: shane knapp <incomplete@gmail.com>

Closes #2596 from shaneknapp/SPARK-3745 and squashes the following commits:

c95eea9 [shane knapp] SPARK-3745 - fix check-license to properly download and check jar
[Build] Post commit hash with timeout messages

[By request](https://github.com/apache/spark/pull/2588#issuecomment-57266871), and because it also makes sense.

Author: Nicholas Chammas <nicholas.chammas@gmail.com>

Closes #2597 from nchammas/timeout-commit-hash and squashes the following commits:

3d90714 [Nicholas Chammas] Revert "testing: making timeout 1 minute"
2353c95 [Nicholas Chammas] testing: making timeout 1 minute
e3a477e [Nicholas Chammas] post commit hash with timeout