Change timezone of the datetime to what browser specifies (#4688)

app/views/admin/accounts/show.html.haml

@@ -24,6 +24,7 @@
         %th= t('admin.accounts.most_recent_activity')
         %td
           - if @account.user_current_sign_in_at
+            %time.formatted{ datetime: @account.user_current_sign_in_at.iso8601, title: l(@account.user_current_sign_in_at) }
               = l @account.user_current_sign_in_at
           - else
             Never
@@ -43,6 +44,7 @@
           %th= t('admin.accounts.push_subscription_expires')
           %td
             - if @account.subscribed?
+              %time.formatted{ datetime: account.subscription_expires_at.iso8601, title: l(account.subscription_expires_at) }
                 = l @account.subscription_expires_at
             - else
               = t('admin.accounts.not_subscribed')