LPS-32252 aui-legends should be 100% width

This is before:
![before](https://f.cloud.github.com/assets/203395/59804/70d0aff4-5be4-11e2-90a4-f0ed7e648127.png)

This is after:
![after](https://f.cloud.github.com/assets/203395/59806/81e31d90-5be4-11e2-949e-004e4f388a7d.png)