Updates version to 0.3.0 in README.
Updates version to 0.3.0 in README.

tptee/Parsimmon,ayanonagon/Parsimmon,tptee/Parsimmon,ayanonagon/Parsimmon,ludovic-coder/Parsimmon,ludovic-coder/Parsimmon,jonsimington/Parsimmon,jonsimington/Parsimmon