Fixed #237: app_running? is more reliable now

Hi @jonasmaturana,

Have a look at the commit, the only slightly odd thing I've done is removing the call to app_running? when catching an exception during a http() call.

The reason for this is that since the new app_runnning implementation calls http(), there would be an infinite loop.

Kudos to @kikyoungkwon for the original fix on the ustwo repo.