Added {{^ to mustache-mode-open-section.

----------------------------------------
Before:

{{#repo}}
  <b>{{name}}</b>
{{/repo}}
{{^repo}}
No repos :(
{{/repo}}

----------------------------------------
After:

{{#repo}}
  <b>{{name}}</b>
{{/repo}}
{{^repo}}
  No repos :(
{{/repo}}

----------------------------------------
Merge pull request #8 from tekezo/master

Resolved an indentation issue of {{^.