Private message enhance

## Summary

Enabled to handle **Private Message**.  In particular:
* view the timeline of private message
* view the related private messages like conversation
* send a private message
* respond to other's private message
* remove own private message

## Images
### Timeline and Private Message Sender Panel

![pm-timeline](https://f.cloud.github.com/assets/2914192/1421069/1a3ffff8-3fe8-11e3-9505-3ba17f2201fe.png)

### Conversation View

![pm-conversation](https://f.cloud.github.com/assets/2914192/1421071/23f6b1ea-3fe8-11e3-82b6-d7f04cae161a.png)

### Dialog

![pm-dialog](https://f.cloud.github.com/assets/2914192/1421074/2d3a9d02-3fe8-11e3-82e1-2e8f91349146.png)

## Explanation

Private Message is **NOT** public, so changed theme color of all components related to **Private Message**.
In addition, the colors was determined by me without others statements.

## An annual excuse

* **NOT** implemented the function to check input error(s) when send message(for example, there is no address.)
    * Private message without address can be viewed by the message's owner only.