Mongo Saver: Save only known top level keys

[glensc]

Mongo Saver: Save known top-level keys

This will prevent Upload or File saver submitting totally arbitrary top-level keys.

[glensc]

Due to this sanitizing that known input is submitted, found a bug that MongoSaver test calls save for multiple profiling:

• https://github.com/perftools/xhgui/blob/9eeadbbad6b418aa97e79bdaed4f98026f4c48e2/tests/Saver/MongoTest.php

The mongodb insert maybe supports inserting multiple records a time:

• xhgui/src/Xhgui/Saver/Mongo.php

  Line 38 in 9eeadbb

  return $this->_collection->insert($data, array('w' => 0));

but the rest of the code in the block assumes single row:

• xhgui/src/Xhgui/Saver/Mongo.php

  Lines 22 to 28 in 9eeadbb

  	if (!isset($data['_id'])) {
  	$data['_id'] = self::getLastProfilingId();
  	}
  	if (isset($data['meta']['request_ts'])) {
  	$data['meta']['request_ts'] = new MongoDate($data['meta']['request_ts']['sec']);
  	}