Adds support for inclusion of variables defined in the gulpfile.js

[deefour]

var fileInclude = require('gulp-file-include');

gulp.task('html', function() {
  return gulp.src([ '*.html' ])
             .pipe(fileInclude({
               data: {
                 "title": "Default Page Title"
               }
             })
             .pipe(gulp.dest('public'));
});

The variables can be overridden by individual @@include(...) statements

@@include("index.html", { "title": "The Homepage" })

[deefour]

I'd love to write tests for this, but am unsure how to run them 😦

[coveralls]

Coverage decreased (-97.06%) when pulling 18e9e06 on deefour:patch-1 into 6c16b44 on coderhaoxin:master.

[haoxins]

@deefour test failed.