Update mustache library to fix rendering of partials

[mnussbaum]

The new cbroglie version of the library is a maintained fork of the original hoisie authored version of the mustache lib. It has fixes for the correct indentation of partials in mustache, as well as additional error handling.

With the old library mustache partial indentation was rendered incorrectly. For example if the first snippet is a file my-partial.mustache:

  indented text

Unindented text
{{> my-partial }}

Would render:

Unindented text
indented text

Now it renders:

Unindented text
  indented text

[belak]

This works for me. Thanks for the update!