Added constant for /simple/all request
Added constant for /simple/all request

Constant for ArangeoDb request /_api/simple/all
cesarsmaniotto/arangodb-php,diabl0/arangodb-php,arangodb/arangodb-php,diabl0/arangodb-php,frankmayer/ArangoDB-PHP,cesarsmaniotto/arangodb-php,arangodb/arangodb-php,frankmayer/ArangoDB-PHP