Gtests for Utilities.cpp (#181)

* Finishing modularization of UsgsAstroLsSensorModel::computeViewingPixel

* Fixes per request

* Removing ISIS references in variable names while I'm here

* Beginning to implement tests for modularization changes in LS sensor model class

* Adding tests for Utilities as well as a few minor modifications

* Making suggested changes and adding test for caculateAttitudeCorrection

* Fixing vector size