Added connection feature to remote/cloud ArangoDB instance

The connection interface (arango_connection.R) has been changed to accommodate connecting to a remote/cloud version of ArangoDB. Mock test data has been added. An example file that provides an illustration of connecting to a remote/cloud instance of ArangoDB and performing operations on it has been added. (arango_ms_basic_tutorial.R). This request subsumes the changes of the earlier request (#3 (closed)) related to adding a type argument to the collection interface. This merge request includes those changes. Please see the attachment for test case results.