Migration to MichelFortin's implementation.

Since flydev has marked his version as deprecated (it was a simple composer port of Michel Fortin's initial project), it seems good to revert the dependency to the stable/continued project.
Removing overriden method for fencedCodeBlocks.

Michel Fortin's implementation is able to handle the fencedCodeBlock without any escaping mecanism.
Updating testsuite to Michel Fortin implementation.

The footnote behaviour has changed during migration. You might want to check out the pr mentionning it : https://github.com/KnpLabs/KnpMarkdownBundle/pull/50
Merge pull request #50 from iammichiel/master

Migration to MichelFortin's implementation.