update to Handlebars 1.0.0-rc.4
fix failing #test_patching_handlebars
fix bug in generate_known_helpers_hash

was previously undetected due to a bug in Handlebars:
https://github.com/wycats/handlebars.js/issues/302
Update README
v0.12.1
Synchronize Sprockets engine registers with Rails

It might be worth considering DRYing up handlebars.rb and
handlebars_assets/engine.rb.
Specify JSON version to silence warning
Add @mark-rushakoff to contributors
v0.12.2
pass scope and locals up the chain, allows regular rails asset helpers etc in HAML and SLIM
nicer rvmrc (no ruby version defined, previously was system)
Allow configure block
v0.12.3
update to Handlebars 1.0.0
v0.13.0
Resister engine using `Sprockets` vs `app.assets`.

In rare cases with other eninges mounted, using `app.assets` engine instnce causes a `can't modify immutable index` errors.
Add @metaskills to contributors
v0.14.0
Revert "Resister engine using `Sprockets` vs `app.assets`."

Not convinced that this is the 'right thing to do'.

This reverts commit c1cea5dc60c3806ca1d45ba16b38457fc748ffc1.
v0.14.1