fix AsciiDoc errors; add escaping where necessary

- use correct delimiter for quote blocks (____ instead of ----)
- use example block delimiters instead of sidebar delimiters for admonition block
- add backslash in front of + in C++
- use backticks to escape inline clojure snippets where necessary
- fix path to templating-with-selmer.asciidoc include file
Merge pull request #191 from mojavelinux/asciidoc-syntax-fixes

fix AsciiDoc errors; add escaping where necessary