Fix setState warning when component unmounts

[danielr18]

The component should avoid calling setState() after it has unmounted, which can happens before the request is completed.

[coveralls]

Coverage increased (+0.8%) to 96.429% when pulling 0535813 on danielr18:master into 147eab1 on esphen:master.

[eliihen]

Awesome! The diff looks great.

I'll merge and get this out in 0.2.1 shortly

Thanks!