resolves #200 upgrade to Asciidoctor 0.1.4

- upgrade asciidoctor gem to 0.1.4
- update install instructions for AsciiDoc
- configure Asciidoctor to output correct <pre> tags for code listings
- set the showtitle attribute so document title is displayed
- set section idprefix & idseparator to be consistent w/ other renderers
- set env-github to allow conditional content when rendering on GitHub
- add tests for admonition (no icon) and source listing
- fix test
Merge remote-tracking branch 'origin/master' into mojavelinux-asciidoctor-0-1-2

* origin/master:
  require newer asciidoc in order to match test data
  add initilize options for rdoc-4.0.x
  Release 1.0.0
  bump version to 1.0.0
  add a markups accessor method for @@markups
  cache file extension regexp instead of recompiling it every time
  fix GitHub::Markup.preload!
  add special cased markdown implementation
  refactor command/gem details into implementation classes
  eager load markdown implementations for fallback
  add :eager option to markup
  defer loading of markups gems until they're first used
  tell ruby what the filename of markups.rb is
  Add tests for RST
  remove rst table border
  Resolve #189 by upgrading org-ruby dependency.

Conflicts:
	Gemfile
Merge pull request #201 from mojavelinux/asciidoctor-0-1-2

* mojavelinux-asciidoctor-0-1-2:
  resolves #200 upgrade to Asciidoctor 0.1.4