Add boolean helpers

[vincent-psarga]

Basically, support simple boolean helpers to introduce a bit of logic in the templates.

• eq to compare equality between items
• includes to check if item2 is included in item 1
• gt to check if item1 is greater than item1
• gte to check if item1 is greater than or equal to item1
• lt to check if item1 is lesser than item1
• lte to check if item1 is lesser than or equal to item1

The idea is to use those helpers inside other helpers (if or unless).

Example:

{{#if (eq name "John")}}
  Hello Johnny!
{{else}}
  Hello {{name}} !
{{/if}}

[d316]

IMHO this diverges from the standard functionality of handlebars, i.e., this feature-set is not a part of the built-in handlebars helpers. Perhaps consider moving this into a plugin lib separate from this lib to keep this consistent with the standard feature-set of handlebars. Cf. https://github.com/jmurphyau/ember-truth-helpers for keeping truth helpers separate from the handlebars proper.

[vincent-psarga]

Thanks for the comment. In fact I'm using truth-helper on another project and I thought it was handlebars built-in.

I'll move that to another gem :)