Add simplest testcases.

For processing single token. I'm going to concentrate on that so far.

For processing a method call.
use eq matcher instead of be

perhaps they can't be `be'
add context to make the given source code valid
add awesome_print as development dependency

I can't read the output of Ripper.sexp without it\!
add classes representing objects returned by Ripper.sexp
add pryrc to easily experiment with ripper
correct invalid class method definition
add metamorphose itself to .pryrc
setup environment to investigate how ripper behaves
try to handle the vcall event
add the metamorphosed source to test_metamorphoser.rb
fix to pass the first spec
add a comment to clarify the reason why save binding
change api

Now a module extending Metamorphose need to implement metamorphose_piece

then Metamorphose#metamorphose_source produces _metamorphose_piece instead of metamorphose_piece

By doing that, Metamorphose#_metamorphose_piece can return its wrapping value assuredly
fix to pass the second spec
correct spec so that MetamorphoseForDescription._metamorphose_piece can get the method's name
append any tokens to @metamorphosed_source
many changes

I've forgotten
initialize @metamorphosed_tokens in initialize to remove overriding parse
add a class to represent a token the metamorphoser's wrapping and source code before/after it