Fix for change in handlebars 2.0

Handlebars 2.0 now renders boolean false as the word "false" instead of an empty string. This broke all tests that returned a false value.

Helpers have now been updated to explicitly return an empty string, so as to maintain compatibility with both Handlebars 1.3 and 2.0.

See https://github.com/wycats/handlebars.js/issues/827
dev-deps: Handlebars 2.0
0.1.3