Handle authentication implicitly
Handle authentication implicitly

When a Client is initialized, the token or username/password is now
passed in which will implicitly authenticate on the first request.

Since related URLs depend on the initial request to the server, this
is now handled at a lower-level.

Signed-off-by: Byron Ruth <e9d71f5ee7c92d6dc9e92ffdad17b8bd49418f98@devel.io>
harvest-platform/harvest-api-client