[applications] Line length cleanup

- shortened long lines with few exeptions (links)
- fixed some obvious typos, still much to do here...
removed ladspavst.linuxaudio.org

- removed the link from the Applications page, because
  the site doesn't exist anymore, see the LAD/LAU
  mailing lists for details (I think in 2013)
expanded README

- added requirement on jekyll version
- added missing text
- added some development notes