Add basic beautify-html js tests
Add handlebars support

This adds a new 'indent_handlebars' option to the beautify-html
formatter.  When not turned on, anything inside handlebars {{ }} will be
treated as normal content as before.

When turned on, Handlebars block expressions (e.g. {{#anything}},
{{/anything}}, and special case {{else}}) are treated identically to
formatted HTML tags and indented properly.

Handlebars expressions inside of HTML tags get spaces on either side.

Handlebars expression in quotes are left unformatted.
Support quotes inside of Handlebars expressions in strings
Merge pull request #321 from quisquous/handlebars

indent_handlebars support, HTML tests