Add settings UI

Summary:
Adds a simple UI for editing settings, a reducer and persistance config for the data.
These values aren't yet used for anything.

Reviewed By: passy

Differential Revision: D17684490

fbshipit-source-id: e76ac43ffa17d3606e59f4a1ccb940e8d9fbd9e8

src/chrome/TitleBar.tsx

@@ -14,6 +14,7 @@ import {
   toggleRightSidebarVisible,
   ACTIVE_SHEET_BUG_REPORTER,
   setFlipperRating,
+  ACTIVE_SHEET_SETTINGS,
 } from '../reducers/application';
 import {
   colors,
@@ -181,6 +182,12 @@ class TitleBar extends React.Component<Props, StateFromProps> {
             icon="bug"
           />
         )}
+        <Button
+          icon="settings"
+          title="Settings"
+          compact={true}
+          onClick={() => this.props.setActiveSheet(ACTIVE_SHEET_SETTINGS)}
+        />
         <ButtonGroup>
           <Button
             compact={true}