Fix typo in Package Activation Panel

The number of activated packages, which took longer than 5ms to activate,
is now displayed correctly.

Before:
![screen shot 2014-03-04 at 16 12 39](https://f.cloud.github.com/assets/256075/2322467/a3f08100-a3b1-11e3-8f71-a98694a7158c.png)

After:
![screen shot 2014-03-04 at 16 27 21](https://f.cloud.github.com/assets/256075/2322468/a89b2a3e-a3b1-11e3-9777-88e058233383.png)