GNUmakefile: phony targets marked as such
OpenStruct-less implementation

no need to keep an OpenStruct instance *and* a Hash.
README mentions HashStruct#foo, HashStruct#foo=
`make gem` builds the gem
README: don't be so harsh on myself
README mentions the license, has a ToC
NoMethodError message mimics ruby core
test treatment of constructor arguments

tests construction from both Array and Hash instances.
rspec: should -> expect (better, safer interface)

hoorray for sanity.