Include name option for all helper calls

All helper calls will have access to `options.name` which is the first id value of the mustache operation.

As part of this the helperMissing call has been simplified to remove the indexed name in order to optimize the call. This is a breaking change.

Fixes #634
Cleanup now unused code in jscompiler
Merge pull request #634 from wycats/name-option

It would be great to have the helper name passed to `blockHelperMissing`