Added the ability to pass string arguments into the processing function ...

Added the ability to pass string arguments into the processing function of a block.  Arguments are passed in an array as a property of the block argument (block.args).  The user could then do this in their html

&lt;!-- htmlbuild:myBlockFn arg1 arg2 --&gt;
 ...
&lt;!-- endbuild --&gt;

Then in the gulp file:

gulp.src(['./index.html'])
    .pipe(htmlbuild({
      myBlockFn: function (block) {
          var args = block.args;
          // processing....
      };

I've written a few test for this which seem to pass.