Add proptools.Int and proptools.IntDefault that behave analogously to proptools.String and proptools.StringDefault. Change-Id: I41fd3417c973c9ff4a5aa6680546b4b893784745
This allows using the various go commands without a GOPATH. Change-Id: I428ad3a4e884b68615e6e73168c5a844bad7c4d4