fix(select-filter): select lists should not display an empty and '-' …

…option

For a demo on what this change will look like see the pull request:

#654 (comment)

src/ng-table/filters/select.html

@@ -3,4 +3,5 @@
         ng-model="params.filter()[name]"
         ng-if="filter == 'select'"
         class="filter filter-select form-control" name="{{name}}">
+    <option style="display:none" value=""></option>
 </select>

src/scripts/04-controller.js

@@ -127,7 +127,7 @@ function($scope, NgTableParams, $timeout, $parse, $compile, $attrs, $element, ng
                         data = [];
                     } else if (angular.isArray(data)) {
                         data.unshift({
-                            title: '-',
+                            title: '',
                             id: ''
                         });
                     }