Separate classes for the different buttons

Also rename RoleButton to ActionButton because it's not being
given a Role any more.

Conflicts:
	src/component-index.js

cherry-picking commit 4a5821e.

src/components/views/elements/RoomDirectoryButton.js

@@ -0,0 +1,37 @@
+/*
+Copyright 2017 Vector Creations Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+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.
+*/
+
+import sdk from '../../../index';
+import PropTypes from 'prop-types';
+
+const RoomDirectoryButton = function(props) {
+    const ActionButton = sdk.getComponent('elements.ActionButton');
+    return (
+        <ActionButton action="view_room_directory"
+            label="Room directory"
+            iconPath="img/icons-directory.svg"
+            size={props.size}
+            tooltip={props.tooltip}
+        />
+    );
+};
+
+RoomDirectoryButton.propTypes = {
+    size: PropTypes.string,
+    tooltip: PropTypes.bool,
+};
+
+export default RoomDirectoryButton;