README: change format to Markdown and add authorship information

This pull request essentially changes the format of the README file to Markdown. It also adds some more information about authorship. The diffstat is the following:

    README    | 47 -----------------------------------------------
    README.md | 42 ++++++++++++++++++++++++++++++++++++++++++
    2 files changed, 42 insertions(+), 47 deletions(-)

Sorry about the last pull request, the merge automator in fact said that it would not be able to merge as the branches were not in sync. Now it seems to be possible to automatically merge the branches as this pull request is based on the last commit of the original branch.