Add elastic callback plugin (#3380) (#3542)

* Add elastic callback plugin

* Capture task failures

* Catch errors and add UTs

* Skip 3.5< python versions and install dependency

* fix lint

* Fix linting

* Fix linting

* Add botmeta

* Apply suggestions from code review

Co-authored-by: Felix Fontein <felix@fontein.de>

* It's not required

* As suggested in the code review OrderedDict has been added to the Python stdlib since version 2.7

* Update plugins/callback/elastic.py

Co-authored-by: Felix Fontein <felix@fontein.de>

Co-authored-by: Felix Fontein <felix@fontein.de>
(cherry picked from commit 905f4dcfa2)

Co-authored-by: Victor Martinez <victormartinezrubio@gmail.com>

.github/BOTMETA.yml

@@ -49,6 +49,9 @@ files:
     maintainers: dagwieers
   $callbacks/diy.py:
     maintainers: theque5t
+  $callbacks/elastic.py:
+    maintainers: v1v
+    keywords: apm observability
   $callbacks/hipchat.py: {}
   $callbacks/jabber.py: {}
   $callbacks/loganalytics.py: