kvm tools: Provide the basic Gitish framework

kvm tools: Provide the basic Gitish framework

- kvm-cmd.h: Adds a new structure cmd_struct to create a table of commands
  and callback function. The structure was copied from tools/perf

- kvm-cmd.c: implements two main functions for command processing.
  kvm_get_command(): searches table for specific command.
  handle_command(): invokes the callback function for a given command.

- kvm-help.[ch] Implements the kvm help command. The function
  list_common_cmds_help() is a copy of similar function in tools/perf.

[ penberg@kernel.org: Add CREDITS-Git file for proper attributions. ]
Signed-off-by: Prasad Joshi <prasadjoshi124@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>