changed default error classes to be less generic
changed default error classes to be less generic

Instead of needing to pass new variables for $field_class and $error_class have prefixed both with gump- to avoid any potential CSS framework clashes with common named classes.
NandoKstroNet/GUMP,bylinggha/GUMP,TaylorHawkes/GUMP,igorclark/GUMP,josecarlosweb/GUMP,pl4g4/GUMP,juanvillegas/GUMP,Wixel/GUMP,aecca/GUMP