Move the old metadata-service datasource to url datasource. This new datasource
checks for the existance of meta-data.json and if it doesn't exist, walks the
meta-data directory to build a metadata blob.
Supports retries with exponential backoff as well as connection
timeouts and the ability to skip SSL/TLS verification.
This commit also refactors datasource and initialize packages
in order to use the new HTTP client.
