Push perf test results to slack app (#6371)

* Add script to publish testnet results to slack

* Obscure webhook URL

* fixup

* Replace read with cat redirection

* Turn back on net restart

* Pick nits

* Make symlink before trying to delete its contents

* Display test config in slack and pick Trents nit not to maybe rm -rf /*

* Clean up results print

* Minor nits

* Turn the test settings back up to 11

* typo

* Shellcheck

* Just a few more fields

* fix payload formatting

* Del clear-config.sh

* Mount secondary

* Add commit SHA link and Grafana time range URL

* Add fancy buttons instead of text URLs

* Tighten up test config display

* Fixup display nits

* chellsheck

* Rebase and fix typo

system-test/testnet-performance/testnet-automation-json-parser.py

@@ -2,6 +2,9 @@
 import sys, json
 
 data=json.load(sys.stdin)
-print[\
-   ([result['series'][0]['columns'][1].encode(), result['series'][0]['values'][0][1]]) \
-   for result in data['results']]
+
+if 'results' in data:
+   for result in data['results']:
+      print result['series'][0]['columns'][1].encode() + ': ' + str(result['series'][0]['values'][0][1])
+else:
+   print "No results returned from CURL request"