switch to vndr

vndr is almost exactly the same as our old good hack/vendor.sh. Except
it's cleaner and it allows to re-vendor just one dependency if needed
(which we do a lot for containers/image).

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

vendor/github.com/pkg/errors/.gitignore

@@ -1,24 +0,0 @@
-# Compiled Object files, Static and Dynamic libs (Shared Objects)
-*.o
-*.a
-*.so
-
-# Folders
-_obj
-_test
-
-# Architecture specific extensions/prefixes
-*.[568vq]
-[568vq].out
-
-*.cgo1.go
-*.cgo2.c
-_cgo_defun.c
-_cgo_gotypes.go
-_cgo_export.*
-
-_testmain.go
-
-*.exe
-*.test
-*.prof

vendor/github.com/pkg/errors/.travis.yml

@@ -1,11 +0,0 @@
-language: go
-go_import_path: github.com/pkg/errors
-go:
-  - 1.4.3
-  - 1.5.4
-  - 1.6.3
-  - 1.7.3
-  - tip
-
-script:
-  - go test -v ./...

vendor/github.com/pkg/errors/README.md

@@ -1,52 +0,0 @@
-# errors [![Travis-CI](https://travis-ci.org/pkg/errors.svg)](https://travis-ci.org/pkg/errors) [![AppVeyor](https://ci.appveyor.com/api/projects/status/b98mptawhudj53ep/branch/master?svg=true)](https://ci.appveyor.com/project/davecheney/errors/branch/master) [![GoDoc](https://godoc.org/github.com/pkg/errors?status.svg)](http://godoc.org/github.com/pkg/errors) [![Report card](https://goreportcard.com/badge/github.com/pkg/errors)](https://goreportcard.com/report/github.com/pkg/errors)
-
-Package errors provides simple error handling primitives.
-
-`go get github.com/pkg/errors`
-
-The traditional error handling idiom in Go is roughly akin to
-```go
-if err != nil {
-        return err
-}
-```
-which applied recursively up the call stack results in error reports without context or debugging information. The errors package allows programmers to add context to the failure path in their code in a way that does not destroy the original value of the error.
-
-## Adding context to an error
-
-The errors.Wrap function returns a new error that adds context to the original error. For example
-```go
-_, err := ioutil.ReadAll(r)
-if err != nil {
-        return errors.Wrap(err, "read failed")
-}
-```
-## Retrieving the cause of an error
-
-Using `errors.Wrap` constructs a stack of errors, adding context to the preceding error. Depending on the nature of the error it may be necessary to reverse the operation of errors.Wrap to retrieve the original error for inspection. Any error value which implements this interface can be inspected by `errors.Cause`.
-```go
-type causer interface {
-        Cause() error
-}
-```
-`errors.Cause` will recursively retrieve the topmost error which does not implement `causer`, which is assumed to be the original cause. For example:
-```go
-switch err := errors.Cause(err).(type) {
-case *MyError:
-        // handle specifically
-default:
-        // unknown error
-}
-```
-
-[Read the package documentation for more information](https://godoc.org/github.com/pkg/errors).
-
-## Contributing
-
-We welcome pull requests, bug fixes and issue reports. With that said, the bar for adding new symbols to this package is intentionally set high.
-
-Before proposing a change, please discuss your change by raising an issue.
-
-## Licence
-
-BSD-2-Clause

vendor/github.com/pkg/errors/appveyor.yml

@@ -1,32 +0,0 @@
-version: build-{build}.{branch}
-
-clone_folder: C:\gopath\src\github.com\pkg\errors
-shallow_clone: true # for startup speed
-
-environment:
-  GOPATH: C:\gopath
-
-platform:
-  - x64
-
-# http://www.appveyor.com/docs/installed-software
-install:
-  # some helpful output for debugging builds
-  - go version
-  - go env
-  # pre-installed MinGW at C:\MinGW is 32bit only
-  # but MSYS2 at C:\msys64 has mingw64
-  - set PATH=C:\msys64\mingw64\bin;%PATH%
-  - gcc --version
-  - g++ --version
-
-build_script:
-  - go install -v ./...
-
-test_script:
-  - set PATH=C:\gopath\bin;%PATH%
-  - go test -v ./...
-
-#artifacts:
-#  - path: '%GOPATH%\bin\*.exe'
-deploy: off