Fix misleading wording in README

Fixes #103.
Improve parser to detect LineBreak independently of renderer.

When checking if it's a newline preceeded by two spaces, look at the input data rather than the output, since the output depends on the renderer implementation.
Merge pull request #107 from shurcooL/master

Improve parser to detect LineBreak independently of renderer.
Use HTML5 recommended style of language on code blocks

For code blocks that contain a certain language of code, the recommended
attribute structure is <pre><code class="language-foo">. This also
corresponds to the behavior expected by various JS syntax highlighters.

The GitHub code block implementation was obsolete, and identical to the
normal implementation except for its attribute structure, so it was
removed.

Closes #108.
Merge pull request #109 from tummychow/html5-code-block

Use HTML5 recommended style of language on code blocks
Fixup tests after 67002b0
Add a simple Travis config
More Travis stuff: better go get, plus build badge
Remove go tip from Travis build matrix
Merge pull request #111 from rtfb/master

Add Travis configuration and a badge