Return valid JSON

The getMetaData function did not return valid JSON, if you ran the
retuned string with `JSON.parse()` it would fail. Valid JSON uses double
qoutes.
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Partial prefix bug fix
Updated README with new helper paths
Merge pull request #159 from adambiggs/master

Fix bug with multiple partials in a template
Merge pull request #158 from pppdns/patch-1

Updated README with new helper paths
Merge pull request #154 from xdamman/fix/tests

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Merge pull request #153 from Saturate/master

Make getMetaData return valid JSON
Bump the version
Bump the handlebars dependency and the r.js one as well
Use global installations of dependencies

Projects where handlebars, underscore and json2 are dependencies of
modules others than require-handlebars may prefer using their existing
libraries installation and require.js paths setup.

The current patch uses common global module IDs for these dependencies,
instead of relying on the shipped ones.
Rely on native's JSON, drop JSON2 depencendy.