cEP 0: Replace markdown for cEPs

[jayvdb]

markdown is a crazy language. rST is slightly better, and that aligns better with being a Python org.

However, we should be a multilingual org, so it is useful to force ourselves to switch languages, testing different bears in the process.

For one, asciidoc has better table support.
http://www.methods.co.nz/asciidoc/newtables.html

[jayvdb]

A nice feature of rst is that we have a bear which should be able to check the syntax of python inside code blocks.
c.f. #124 (comment)

[jayvdb]

Another pretty bad case. #124 (comment)