Quality of life improvements

[RyanJarv]

• Don't kill Pacu on Ctrl-C
  • Ctrl-D is the right way to end a shell session, Ctrl-C should more likely kill a running module.
• Support using credentials from the environment (including IMDS). Default AWS credential lookup behavior #273
  • May make sense not to do this by default since you want to ensure you're running in the right environment. (alternatively we could display the account name or # in the shell prompt).
• Fix command completion.
• Save command history across sessions.

Other things to think about:

• Naming..
  • Not consistent, every conceivable combination of __, enum, and the name of the service has been used.
  • Some names are misleading, iam__enum_roles isn't for enumerating roles in the current account, as one might suspect.
  • Why are there two dashes in modules? It's hard enough as is to justify one.
  • Too verbose, iam__enum_users_roles_policies_groups combines the worst parts of Java and python.
• Module testing

[h00die]

Fix command completion.

#424

[h00die]

• Save command history across sessions.

#435

[EduardSchwarzkopf]

Module testing

#436