Basic remote database implementation

Adds the grunt http module
Allows vvv.json to specify a remote database
If a remote database is specified some grunt commands become available

This is an MVP. In the future we may want to:
* Handle .sql.gz remote files
* Delete remote database files after install. (they can be re-downloaded, no need to keep)
* Handle the case where there's a local DB file and a remote DB specified.
Use regex to grab the filename out of the remote database URL
Merge pull request #27 from tddewey/dev

Basic remote database implementation