Open to PR for posting to _find?

[silverbackdan]

Before I submit a PR writing the function into CouchDBClient.php (which would be pretty simple) - would you be open to having this to quickly send a POST request to the database _find endpoint to run Mango queries?

I'd imagine something like:

    /**
     * Find a documents with a mango query
     *
     * @param array|string $query
     * @return HTTP\Response
     */
    public function findRequest($query)
    {
        if (!is_string($query) {
            $query = json_encode($query);
        }
        $findPath = '/' . $this->databaseName . '/_find';
        return $this->httpClient->request('POST', $findPath, $query);
    }

[robsonvn]

#86 already covers this, I hope you enjoy.