Checking isEmpty on features causes extraneous console.logs

[bttf]

Using Ember.isEmpty on the features service outputs in the console:

Feature flag off: size
Feature flag off: length

I can probably look at this later since it seems like an easy fix. Using this as a reminder

[buschtoens]

This is, because by the checking presence, you are accessing the feature flag, through the unknownProperty trap, which defaults to false, if the flag is not set. So this would not work anyway. See #31 for more ccontext.

What you would require is something like an isSet method.