Merge branch 'feature-php-driver-improve'

connector/php/exampleCall.php

connector/php/exampleInsert.php

connector/php/exampleSelect.php

connector/php/exampleUpdate.php

connector/php/tarantool.c

connector/php/tarantool.h

connector/php/test/admin.phpt

connector/php/test/bin/run-test.bash

connector/php/test/call.phpt

connector/php/test/delete.phpt

connector/php/test/errors.phpt

connector/php/test/etc/php.ini

connector/php/test/etc/tarantool_box.cfg

connector/php/test/insert.phpt

connector/php/test/lib/lua/test.lua

connector/php/test/lib/php/tarantool_utest.php

connector/php/test/run-test

connector/php/test/select.phpt

connector/php/test/update_fields.phpt