Refactor helper call signature.

* Make the default call signature be `params, hash, options, env`.
* Remove `options.hash`.
* Ensure internal helpers are bound to the context.
* Remove `options.context`.
Merge pull request #127 from rwjblue/refactor-hook-signature

Refactor helper call signature.
Fix broken test
Merge pull request #130 from mmun/fix-test

Fix broken test
Fix test comment
Remove isTop in favor of a downstream implementation.
Merge pull request #131 from rwjblue/remove-isTop

Remove isTop in favor of a downstream implementation.
Keep CJS and AMD output split in dist/.

Add `lib/` for ES6 output.
Merge pull request #132 from rwjblue/keep-builds-split

Keep CJS and AMD output split in dist/.
Prepare for publishing to NPM.

* Ensure that `require('htmlbars')` works properly.
* Bump version.
Merge pull request #133 from rwjblue/prepare-for-npm-publishing

Prepare for publishing to NPM.
Ensure dist/ is published to NPM.
Merge pull request #134 from rwjblue/fix-published-files

Ensure dist/ is published to NPM.
Simplify runtime dependencies.
Make htmlbars-test-helpers package.

This allows much easier sharing with Ember.
Merge pull request #135 from rwjblue/simplify-runtime-deps

Simplify runtime dependencies.
Bump version.
Done relative path changes for the script tags
Merge pull request #136 from MatrixZ/file-path-demo-file

Done relative path changes in the demo file
Allow hash arguments to contain dashes (and reserved words).