Replace MatrixClient.isCryptoEnabled by MatrixClient.getCrypto (#140)

* Replace `MatrixClient.isCryptoEnabled` by `MatrixClient.getCrypto`

* Cast `cryptoEnabled` as `boolean`

* Fix `MatrixChat-test`

(cherry picked from commit 950ab1940bfcea9443f03284f9175d319c13a44c)

src/components/structures/RoomView.tsx

@@ -1461,7 +1461,7 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
         // set the state immediately then update, so we don't scare the user into thinking the room is unencrypted
         this.setState({ e2eStatus });
 
-        if (this.context.client.isCryptoEnabled()) {
+        if (this.context.client.getCrypto()) {
             /* At this point, the user has encryption on and cross-signing on */
             e2eStatus = await shieldStatusForRoom(this.context.client, room);
             RoomView.e2eStatusCache.set(room.roomId, e2eStatus);