remove old MDL wrapper directives (#2095)

- remove mdl-button directive
- remove mdl-tooltip directive

ng2-components/ng2-activiti-form/src/components/start-form.component.html

@@ -18,7 +18,7 @@
             </div>
             <div *ngIf="showOutcomeButtons && form.hasOutcomes()" class="mdl-card__actions mdl-card--border" #outcomesContainer>
                 <button *ngFor="let outcome of form.outcomes"
-                        alfresco-mdl-button
+                        md-button
                         [disabled]="!isOutcomeButtonEnabled(outcome)"
                         [class.mdl-button--colored]="!outcome.isSystem"
                         [class.activiti-form-hide-button]="!isOutcomeButtonVisible(outcome, form.readOnly)"

ng2-components/ng2-activiti-form/src/components/widgets/container/container.widget.html

@@ -3,10 +3,10 @@
         <h4 class="container-widget__header-text" id="container-header"
             [class.collapsible]="content?.isCollapsible()">
             <button *ngIf="content?.isCollapsible()"
-                    alfresco-mdl-button
+                    md-icon-button
                     class="mdl-button--icon"
                     (click)="onExpanderClicked()">
-                <i class="material-icons">{{ content?.isExpanded ? 'expand_less' : 'expand_more' }}</i>
+                <md-icon>{{ content?.isExpanded ? 'expand_less' : 'expand_more' }}</md-icon>
             </button>
             <span (click)="onExpanderClicked()" id="container-header-label">{{content.name}}</span>
         </h4>