def commit
      sha1 = index.commit(@options[:message], parents, actor, nil, @wiki.ref)
      @callbacks.each do |cb|
        cb.call(self, sha1)
      end
      sha1
    end
def commit
      sha1 = index.commit(@options[:message], parents, actor, nil, @wiki.ref)
      @callbacks.each do |cb|
        cb.call(self, sha1)
      end
      sha1
    end
Writes the commit to Git and runs the after_commit callbacks.

 Returns the String SHA1 of the new commit.