cmd/gomote: add push --dry-run flag, ignore some auto-generated files
cmd/gomote: add push --dry-run flag, ignore some auto-generated files

Change-Id: I332443eec89a15a29c1f3a0f7856a1f3c34ae0ee
Reviewed-on: https://go-review.googlesource.com/41677
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/build,golang/build,golang/build,golang/build