Custom build of highlight.js to provide handlebars consistency.

Eliminates all discrepancies between component tags (e.g. `gravatar-image`), tags marked as keywords (e.g. `each`) and dasherized tags (e.g. `link-to`). This should be revisited in highlight.js.
Merge pull request #705 from dgeb/cleanup-handlebars-highlighting

Custom build of highlight.js to provide handlebars consistency.