Add logs command

[renehernandez]

New command to be able to see logs from the deployed applications. Example invocations:

appfile logs <app_name> -e <env> -f </path/to/appfile.yaml 

appfile logs <app_name> --component <component name> -e <env> -f </path/to/appfile.yaml>

Flags:

• Support for -t/--tail option to follow the logs live
• Support selecting the type of logs to show (build, deploy, run). Should default to run

[renehernandez]

Not sure if this is worth it at the moment. This command is per app specific and the results can be already obtained with doctl apps logs.

I'll leave it open in case there is demand in the future