Using session_secure

https://metacpan.org/pod/Dancer::Config#session_secure

For now the cookie does not have secure flag:
![screen shot 2014-03-10 at 19 18 12](https://f.cloud.github.com/assets/47263/2375033/41c66f3e-a867-11e3-81c4-6b809bac1014.png)