Improve sfMessage structure to match angular-material style.

Fix input label position.
Fix checkbox display initialisation.

Author: RudolfFrederiksen

material-decorator.js

@@ -5,6 +5,7 @@
                sf-changed="form"
                ng-disabled="form.readonly"
                schema-validate="form"
+               sf-material-class="md-checked"
                class="{{::form.fieldHtmlClass}}"
                name="{{::form.key|sfCamelKey}}"
                aria-label="{{::form.title}}">

material-decorator.min.js

@@ -1,6 +1,6 @@
 <md-input-container class="schema-form-{{::form.type}} {{::form.htmlClass}}"
-                    ng-class="{'md-input-has-value': model['{{form.key.join('\'][\'')}}'], 'has-error': hasError(), 'has-success': hasSuccess(), 'has-feedback': form.feedback !== false}"
-                    sf-messages sf-layout>
+                    ng-class="{'has-error': hasError(), 'has-success': hasSuccess(), 'has-feedback': form.feedback !== false}"
+                    sf-messages sf-layout sf-material-class="md-input-has-value">
   <label  ng-show="showTitle()" for="{{::form.key|sfCamelKey}}">{{::form.title}}</label>
   <input sf-field-model
          ng-show="::form.key"