Add logging to Hub client

[chris-crone]

- What I did
Added a visible --verbose flag and a hidden --trace flag to help debugging. I've only added logs to the Hub client for now.

- How to verify it
Note that --trace his hidden in the help

$ ./bin/hub-tool --help
A tool to manage your Docker Hub images

Usage:
  ./bin/hub-tool
  ./bin/hub-tool [command]

Available Commands:
  account     Manage your account
  help        Help about any command
  org         Manage organizations
  repo        Manage repositories
  tag         Manage tags
  token       Manage Personal Access Tokens
  version     Version information about this tool

Flags:
  -h, --help      help for ./bin/hub-tool
      --verbose   Print logs
      --version   Display the version of this tool

Use "./bin/hub-tool [command] --help" for more information about a command.

$ ./bin/hub-tool account info --verbose
DEBU[0000] HTTP GET on: https://hub.docker.com/v2/user/ 
DEBU[0000] HTTP GET on: https://hub.docker.com/api/billing/v4/accounts/7cc20906ae28482e822084af305ae76a/hub-plan 
DEBU[0000] bad status code "403 Forbidden": {"message":"access to the resource is forbidden with personal access token"} 
Error: bad status code "403 Forbidden": access to the resource is forbidden with personal access token

$ /bin/hub-tool account info --trace  
DEBU[0000] HTTP GET on: https://hub.docker.com/v2/user/
...
<lots of raw request data>

[silvin-lubecki]

nit: %#v should have better formatting

%v the value in a default format when printing structs, the plus flag (%+v) adds field names
%#v a Go-syntax representation of the value

[chris-crone]

Yeah, there are annoying things with #v though like it prints pointers instead of values... e.g.:

#v: URL:(*url.URL)(0xc00012a2d0)
+v: URL:https://hub.docker.com/v2/user/

[silvin-lubecki]

LGTM