Display proper error message when shift cannot find shift.json

[sparshadotel]

Commands:

shift-cli add env
shift deploy dev

Debug Output

panic: Error reading file.: open /tmp/shift.json: no such file or directory

goroutine 1 [running]:
github.com/leapfrogtechnology/shift/core/services/storage.failOnError(...)
	/home/sparsha/go/src/github.com/leapfrogtechnology/shift/core/services/storage/storage.go:14
github.com/leapfrogtechnology/shift/core/services/storage.Read(0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/home/sparsha/go/src/github.com/leapfrogtechnology/shift/core/services/storage/storage.go:24 +0x23b
github.com/leapfrogtechnology/shift/cli/internals/env.Run()
	/home/sparsha/go/src/github.com/leapfrogtechnology/shift/cli/internals/env/env.go:26 +0x37
github.com/leapfrogtechnology/shift/cli/cmd.AddEnv(...)
	/home/sparsha/go/src/github.com/leapfrogtechnology/shift/cli/cmd/env.go:9
github.com/leapfrogtechnology/shift/cli/cmd.Initialize.func4(0xc0000b86e0, 0x0, 0xc0001eebd0)
	/home/sparsha/go/src/github.com/leapfrogtechnology/shift/cli/cmd/cmd.go:57 +0x21
github.com/urfave/cli.HandleAction(0xa8f4c0, 0xbac578, 0xc0000b86e0, 0xc0000b86e0, 0x0)
	/home/sparsha/go/src/github.com/urfave/cli/app.go:523 +0xbe
github.com/urfave/cli.Command.Run(0xb78136, 0x3, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/home/sparsha/go/src/github.com/urfave/cli/command.go:174 +0x521
github.com/urfave/cli.(*App).RunAsSubcommand(0xc00022a380, 0xc0000b8420, 0x0, 0x0)
	/home/sparsha/go/src/github.com/urfave/cli/app.go:404 +0x889
github.com/urfave/cli.Command.startApp(0xb780be, 0x3, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/home/sparsha/go/src/github.com/urfave/cli/command.go:329 +0x84f
github.com/urfave/cli.Command.Run(0xb780be, 0x3, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/home/sparsha/go/src/github.com/urfave/cli/command.go:102 +0x9c4
github.com/urfave/cli.(*App).Run(0xc00022a1c0, 0xc0000b2040, 0x4, 0x4, 0x0, 0x0)
	/home/sparsha/go/src/github.com/urfave/cli/app.go:276 +0x71c
github.com/leapfrogtechnology/shift/cli/cmd.Initialize(0xc000215f58, 0xbac4f8, 0x0)
	/home/sparsha/go/src/github.com/leapfrogtechnology/shift/cli/cmd/cmd.go:66 +0x20b
main.main()
	/home/sparsha/go/src/github.com/leapfrogtechnology/shift/shift.go:17 +0x8e

Expected Behaviour

shift.json is not present in this directory.
Please add shift.json or initialize with shift-cli setup