This update contains more black-box tests as part of the attributes code review....

This update contains more black-box tests as part of the attributes code review. I have confirmed by eyeball that every executable line of attributes.h is now getting hit in coverage testing. This can only be eyeballed at the moment because of templates. (There is 1 function that is not being touched, something included from NodeTemplate: _ZNK4CVC44expr4attr16AttributeManager12getAttributeINS0_9AttributeINS_6theory15RewriteCacheTagENS_12NodeTemplateILb0EEENS1_19NullCleanupStrategyELb0EEEEENT_10value_typeEPNS0_9NodeValueERKSB_)