ethpm registry explore [URI]

[njgheorghita]

A new subcommand for ethpm registry that would accept any valid registry uri and display the available packages and their manifest uris that are available on the registry (similar display to ethpm list).

How can it be fixed?

• A new command (explore) added to the ethpm registry command that requires a URI argument.
• Then validate that this is a valid registry uri.
• Then make a call to the blockchain to fetch all available packages via the web3.pm module.
• Display the available packages in a manner similar to ethpm list.

For testing it would be nice to have a local chain spun up to test against rather than using infura and the mainnet - we should be able to avoid some of the challenges ran into here since we're just reading from the blockchain rather than cutting a new release.

[corydickson]

It might also be useful to allow the user to provide an alias of a registry that's already added. Some immediate blockers might be related to #85 since we would not be able to guarantee a properly formatted URI. Where as it's easier to validate a registry_uri of the format erc1319://0xDEADbeef

I'll start on this initial approach and see how far I can get

[njgheorghita]

Great! I imagine this would be fairly similar to activate_registry() in commands/registry.py - in terms of how we handle using an alias. Agreed that it might be funky until #85 drops - but if we follow the activate_registry pattern - then integrating these down the road shouldn't be too complex.... I hope