Allow downloading of AuthKeyPair private keys if they are available

[mansam]

Implements https://bugzilla.redhat.com/show_bug.cgi?id=1490979

[mzazrivec]

@mansam Could you please address the rubocop issues shown above? (with the exception of auth_key_pair_cloud_center.rb)

[mansam]

@mzazrivec of course :)

[miq-bot]

Checked commits mansam/manageiq-ui-classic@8e198d7~...7135dfb with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
5 files checked, 2 offenses detected

app/helpers/application_helper/toolbar/auth_key_pair_cloud_center.rb

• ❗ - Line 21, Col 11 - Layout/AlignHash - Align the elements of a hash literal if they span more than one line.
• ❗ - Line 22, Col 72 - Layout/MultilineMethodCallBraceLayout - Closing method call brace must be on the line after the last argument when opening brace is on a separate line from the first argument.