Merge gitjob binary into fleetcontroller binary

[manno]

This makes our release scripts easier and reduced the image size by about 50mb.

WIP branch: https://github.com/manno/fleet/commits/merge-binaries/

Gitjob will be a subcommand of fleetcontroller:

Usage:
  fleet-manager [flags]
  fleet-manager [command]

Available Commands:
  agentmanagement
  cleanup
  completion      Generate the autocompletion script for the specified shell
  gitjob
  help            Help about any command

Image size, after merging gitjob and gitcloner:

# Before
rancher/fleet      357MB

# After
rancher/fleet     309MB