Implement resend functionality for failed messages, and update the icons...

... we use for pending and failed messages

Pending message:
![image](https://cloud.githubusercontent.com/assets/1035315/3599101/079eddb2-0ceb-11e4-8f6e-524288c9c677.png)

Failed message:
![image](https://cloud.githubusercontent.com/assets/1035315/3599103/0f9715b6-0ceb-11e4-8f56-7bb587609c16.png)
Tooltip when hovering:
![image](https://cloud.githubusercontent.com/assets/1035315/3599107/1a8bfcde-0ceb-11e4-89d3-e1c52d7f6fe0.png)

After resending message:
![image](https://cloud.githubusercontent.com/assets/1035315/3599111/24741038-0ceb-11e4-84a5-804ca6dbbfbf.png)