Remove duplicate test in html_compiler_test
Merge pull request #167 from oneeman/remove-duplicate-test

Remove duplicate test in html_compiler_test
Add compiler plugins.

AST plugins allow consumers to preprocess and manipulate the AST. This
allows more efficiency in final compiled output and helps downstream
consumers use much more idiomatic helper code but provide a human
readable usage.

For example:

```javascript
{{#each foo in bar}}
{{/each}}
```

Can be preprocessed and transformed into:

```javascript
{{#each bar keyword="foo"}}
{{/each}}
```
Merge pull request #168 from rwjblue/add-ast-plugins

Add compiler plugins.
Bump version to v0.1.12.
Provide more information on mis-matched start/end tags.
Merge pull request #171 from rwjblue/make-mismatched-errors-more-helpful

Provide more information on mis-matched start/end tags.
Cleanup hooks
Merge pull request #172 from mmun/cleanup-hooks

Cleanup hooks
A classList based add/removeClasses, setAttribute fallback