Bug 23222: Update plugins-home.tt with new ENABLE/DISABLE flag name

At some point of history, the flag to indicate if a plugin was enabled/disabled was called "enabled", now it's called "is_enabled"

To test:
1) get a fresh master copy
2) Enable plugins
3) Install any plugin
CHECK => plugin appears as disabled
      => If you try to enable it, it just appears as disabled just the same
4) Apply this patch
5) Reload page
SUCCESS => plugin appears as enabled
        => enable / disable action works again
6) Sign off

Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

koha-tmpl/intranet-tmpl/prog/en/modules/plugins/plugins-home.tt

@@ -79,7 +79,7 @@
                                 <tr>
                                     <td>
                                         <strong>[% plugin.metadata.name | html %]</strong>
-                                        [% IF ( plugin.enabled ) %]
+                                        [% IF ( plugin.is_enabled ) %]
                                             <span class="label label-primary">ENABLED</span>
                                         [% ELSE %]
                                             <span class="label label-default">DISABLED</span>
@@ -131,7 +131,7 @@
                                                     [% END %]
                                                     [% IF ( CAN_user_plugins_manage ) %]
                                                             <li><a class="uninstall_plugin" data-plugin-name="[% plugin.metadata.name | html %]" href="/cgi-bin/koha/plugins/plugins-uninstall.pl?class=[% plugin.class | html %]"><i class="fa fa-trash fa-fw"></i> Uninstall</a></li>
-                                                        [% IF ( plugin.enabled ) %]
+                                                        [% IF ( plugin.is_enabled ) %]
                                                                 <li><a class="enable_plugin" data-plugin-name="[% plugin.metadata.name | html %]" href="/cgi-bin/koha/plugins/plugins-enable.pl?class=[% plugin.class | html %]&method=disable"><i class="fa fa-pause fa-fw"></i> Disable</a></li>
                                                         [% ELSE %]
                                                                 <li><a class="enable_plugin" data-plugin-name="[% plugin.metadata.name | html %]" href="/cgi-bin/koha/plugins/plugins-enable.pl?class=[% plugin.class | html %]&method=enable"><i class="fa fa-play fa-fw"></i> Enable</a></li>