add findFirst and Find() like phalcon

[todo]

baka/src/Elasticsearch/Objects/Documents.php

Lines 235 to 239 in 010eca9

	* @todo add findFirst and Find() like phalcon
	*
	* @param string $sql
	*
	* @return array

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This issue was generated by todo based on a todo comment in 010eca9 when #115 was merged. cc @bakaphp.