fleshed out drupal extension page.
Merge pull request #8 from stopfstedt/behat-drupal

fleshed out drupal extension page.
fixed namespace.
confusion reigns.
some cleanup.
added learn more section
tightened up headline.
fleshed out 'building websites' page.
Merge pull request #9 from stopfstedt/building_websites

fleshed out 'building websites' page.
got rid of double implement
questions questions
removed appendix after moving requirements up.

links for further reading are in the individual pages.
fixed next page link.
removed obsolete document
added next page link.