Checkbox disabled when 0 event logs

The 'select all' box on event log page should be disabled when
there are no event logs presented to the user. Also adds a
message to the user when there are no logs or there are no logs
with their selected filters applied.

Resolves openbmc/phosphor-webui#44

Tested: Checked that correct user message appears when there are
        no logs and when the logs are all filtered out. Also that
        when there are no logs presented to the user, the select
        all box is disabled.

Change-Id: I3106426a72d2148a323ceed978bcdd5515096e2b
Signed-off-by: beccabroek <beccabroek@gmail.com>
diff --git a/app/server-health/controllers/log-controller.html b/app/server-health/controllers/log-controller.html
index 0a5dfab..0a985c5 100644
--- a/app/server-health/controllers/log-controller.html
+++ b/app/server-health/controllers/log-controller.html
@@ -29,7 +29,7 @@
     <div id="event__actions-bar" class="row header__actions-bar no-margin">
       <div class="column small-1 large-1 event-log__col-check">
         <label class="control-check">
-          <input type="checkbox" name="events__check-all" ng-model="all" ng-checked="((filteredLogs|filter:{selected: true}).length == filteredLogs.length) && filteredLogs.length != 0"/>
+          <input type="checkbox" name="events__check-all" ng-disabled="filteredLogs.length === 0" ng-model="all" ng-checked="((filteredLogs|filter:{selected: true}).length == filteredLogs.length) && filteredLogs.length != 0"/>
           <span class="control__indicator"></span>
         </label>
       </div>
@@ -59,6 +59,7 @@
         </div>
       </div>
     </div>
+    <div class="empty__logs" ng-if="filteredLogs.length === 0">{{filteredLogs.length === logs.length ? 'No events have been logged yet.' : 'There are no events that match the selected criteria.'}}</div>
     <log-event
       dir-paginate="event in (filteredLogs = (logs|filter:filterBySeverity|filter:filterByStatus|filter:filterByDate|filter:filterBySearchTerms | orderBy:'-Id'))| itemsPerPage: itemsPerPage"
       event="event"