Remove {PRERELEASE} links that may become unlinkable

MSP-11356

Links won't work on master.
Change version for branch

MSP-11346
Add redcarpet as runtime dependency

MSP-11356

Markdown files, such as README.md and CONTRIBUTING.md won't be processed
correctly without redcarpet.
Add back jruby support

MSP-11356

metasploit-version supports JRuby, so metasploit-yard needs to too even
if I can't get the cucumber features to run for JRuby.
Optimize requires/autoloads

MSP-11356
Support both combined and separate export in rvm env

MSP-11356

Hopefully, support both the rvm env format I and travis-ci have and the
different one that Sam Huckins has on his machine since we can't figure
out why the `rvm env` format is different.
Merging PR #4, markdown parsing fixes

MSP-11356