Changed checks for existence of traits in test to use same method as code
Changed checks for existence of traits in test to use same method as code

Because this library is designed to be compatible with PHP 5.3, we need
some way of checking for the existence of traits.
As discussed in issue #43, the aim is to standardise on checking to see
whether or not the method "class_uses" exists.

mrferos/Aura.Di,dstockto/Aura.Di,silentworks/Aura.Di,cxj/Aura.Di,jakejohns/Aura.Di,auraphp/Aura.Di