Embed Handlebars parser into htmlbars-compiler.

* Embed required Handlebars parser modules into htmlbars-compiler.
* Migrate to broccoli-funnel instead of broccoli-static-compiler.
* Add htmlbars-utils package for safe-string (otherwise handlebars modules would be needed for most packages).

This allows HTMLBars to be developed independently of specific Handlebars version.  Whatever version is required, will be embedded and downstream consumers do not have to match versions.

Specifically, it allows Ember's test suite (which uses Handlebars 2.0) to use HTMLBars (which requires Handlebars 1.3).

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Changes to Ember build system to match this will be in a follow-up Ember PR.
Yeah, but this is only temporary. We can remove once Ember no longer needs two different handlebars versions.