Test email configuration during setup (#1144)

* create proper test message and use correct env var for from address. designed to work with sandboxed AWS ses

* use actionmailer in configuration test rake task

* remove mailfactory gem

* tidy up Gemfile and gem lock

* fix rubocop issues

* Update configuration.rake

Co-authored-by: Ahmad Farhat <ahmad.af.farhat@gmail.com>
Co-authored-by: Ahmad Farhat <ahmad.farhat@blindsidenetworks.com>
1 job for release-2.7.5