use `Module.nesting` in ax88179.rb

instead of hardcoded class name
use `Module.nesting` in ax88772.rb

instead of hardcoded class name
use `Module.nesting` in mcs783x.rb

instead of hardcoded class name
remove constraint that tokens can't start w/ digit

Class names are now completely hidden from the user.  This
commit works by adding a prefix to all Cask class names, which
is considered to be an ugly transitional hack on the way to
representing individual Casks as instances.
Merge pull request #7822 from rolandwalker/allow_leading_numbers

Remove constraint that Cask tokens cannot start with digits