smokeTestRelease.py should be more user friendly [LUCENE-5783]

If one runs "python dev-tools/scripts/smokeTestRelease.py" then you get no usage instructions; you get an unhelpful error. It should contain help on how to invoke it.

Furthermore, if would be nice if it inferred the svn release version and the distribution version by assuming a conventional URL format. For example: "http://people.apache.org/\~rmuir/staging_area/lucene_solr_4_9_0_r1604085/"
is 1604085 and 4.9.0. Or, at least remind you that the URL may contain this info.

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Migrated from [LUCENE-5783](https://issues.apache.org/jira/browse/LUCENE-5783) by David Smiley (@dsmiley), updated Apr 20 2017

Start with dev-tools/scripts/smokeTestRelease.py and run the documented command from the issue to inspect its current error behavior. Update the script so an invocation without usable arguments explains how to use it, and handle the example staging URL by extracting or clearly describing the release and SVN versions; verify the command's resulting help and error output.

Written by the indexing model from the issue text.