Watermarks are not passed to reporters

[nmalaguti]

Watermarks are not currently passed in the options to each reporter.

Config:

coverageReporter: {
  watermarks: {
    statements: [ 50, 75 ],
    functions: [ 50, 75 ],
    branches: [ 50, 75 ],
    lines: [ 50, 75 ]
  }
}

watermarks, which is defined on config, is not merged into options before being passed into istanbul.Report.create.

var config = rootConfig.coverageReporter || {};
// omitted
this.onRunComplete = function(browsers) {
  reporters.forEach(function(reporterConfig) {
// omitted
    var options = helper.merge({}, reporterConfig, {
      dir : outputDir,
      sourceStore : new SourceCacheStore({
        sourceCache: sourceCache
      })
    });
    var reporter = istanbul.Report.create(reporterConfig.type || 'html', options);
// omitted
  });
};