Add misc plugins
Add misc plugins

What plugins and why?
- envinject: more flexible env var manipulation
- rich-text-publisher: render the HTML that ghprb outputs in build
  descriptions
- pegdown-formatter: if we want to render Markdown in build / job
  descrptions

samsung-cnct/kraken-ci,maratoid/kraken-ci,maratoid/kraken-ci,samsung-cnct/kraken-ci,samsung-cnct/kraken-ci,maratoid/kraken-ci