Added column 'status' to replication screen

[yrudman]

related BZ:
https://bugzilla.redhat.com/show_bug.cgi?id=1540688

Issue described in BZ: replication screen throws error if replication on one of remote server was not set-up correctly.
After merging ManageIQ/pg-pglogical#20 corrupted subscription would be shown but without any indication that replication set-up is invalid

This PR adding column status to UI which would have value down in for not working subscriptions

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1550119

BEFORE:

AFTER:

@miq-bot add-label replication, enhancement, gaprindashvili/yes

\cc @carbonin @martinpovolny

[miq-bot]

@yrudman Cannot apply the following label because they are not recognized: replication

[miq-bot]

Checked commit yrudman@9700419 with ruby 2.3.3, rubocop 0.52.0, haml-lint 0.20.0, and yamllint 1.10.0
2 files checked, 1 offense detected

**

• 💣 💥 🔥 🚒 - Linter/Haml - Linter::Haml STDERR:

warning: parser/current is loading parser/ruby23, which recognizes
warning: 2.3.5-compliant syntax, but you are running 2.3.3.
warning: please see https://github.com/whitequark/parser#compatibility-with-ruby-mri.

[carbonin]

Nice! Thanks for doing this @yrudman

[simaishi]

Gaprindashvili backport details:

$ git log -1
commit ca006bd631e6b0115669b552292204cb140c3215
Author: Milan Zázrivec <[email protected]>
Date:   Mon Feb 5 10:03:54 2018 +0100

    Merge pull request #3370 from yrudman/added-status-column-to-replication-screen
    
    Added column 'status' to replication screen
    (cherry picked from commit 661d893f569b4ea4f92e1daa0e6852d8043d3d04)
    
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1552880