fix: Set notebook filter font-style

- Use common font-style which is widely used in zeppelin
- Modify inlined font css while removing some useless properties which have default value

`font-style`, `font-variant`, `font-weight` default value is already `normal`

see http://www.w3schools.com/csSref/pr_font_font.asp

zeppelin-web/src/app/home/home.css

@@ -171,7 +171,8 @@ a.navbar-brand:hover {
   color: #000;
   height: 28px;
   width: 200px;
-  font: normal normal normal 14px/1 FontAwesome;
+  font-size: 14px;
+  font-family: 'Helvetica Neue', Helvetica, Arial, 'FontAwesome', sans-serif;
 }
 
 .dropdown-submenu {

zeppelin-web/src/components/filterNoteNames/filter-note-names.html

@@ -11,4 +11,5 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 -->
-<input type="text" class="note-name-query form-control" ng-click="$event.stopPropagation()" placeholder="&#xf002 Filter" ng-model="$parent.query.q" />
+<input type="text" class="note-name-query form-control" ng-click="$event.stopPropagation()"
+       placeholder="&#xf002 Filter" ng-model="$parent.query.q" />