Remove build dependency on `godep`

Instead of using `godep path`, we can simply set the GOPATH directly to
point to the Godeps/_workspace. We can still use `godep` to manage the
dependencies on the Godeps/ tree, but we don't need to have it available
for straight builds from git.

v2: Rebased and moved to inside kube::setup_go_environment() function.

Tested:
- Built it without godep in $PATH:
  $ hack/build-go.sh
- Ran unit tests without godep in $PATH:
  $ hack/test-go.sh
- Retested after rebase.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>

README.md

@@ -67,7 +67,7 @@ The commands above will not work if there are more than one directory in ``$GOPA
 
 ### godep and dependency management
 
-Kubernetes uses [godep](https://github.com/tools/godep) to manage dependencies. Please make sure that ``godep`` is installed and in your ``$PATH``.
+Kubernetes uses [godep](https://github.com/tools/godep) to manage dependencies. It is not required for building Kubernetes but it is required when managing dependencies under the Godeps/ tree. Please make sure that ``godep`` is installed and in your ``$PATH``.
 
 #### Installing godep
 There are many ways to build and host go binaries. Here is an easy way to get utilities like ```godep``` installed:

docs/getting-started-guides/gce.md

@@ -9,7 +9,7 @@
 4. You must have Go (version 1.2 or later) installed: [www.golang.org](http://www.golang.org).
 5. You must have the [`gcloud` components](https://developers.google.com/cloud/sdk/) installed.
 6. Ensure that your `gcloud` components are up-to-date by running `gcloud components update`.
-7. Install godep. [Instructions here](https://github.com/GoogleCloudPlatform/kubernetes#installing-godep)
+7. Install godep (optional, only required when modifying package dependencies). [Instructions here](https://github.com/GoogleCloudPlatform/kubernetes#installing-godep)
 8. Get the Kubernetes source:
 
         git clone https://github.com/GoogleCloudPlatform/kubernetes.git

docs/getting-started-guides/vsphere.md

@@ -18,7 +18,7 @@
    go get github.com/vmware/govmomi/govc
    ```
 
-5. Install godep. [Instructions here](https://github.com/GoogleCloudPlatform/kubernetes#installing-godep)
+5. Install godep (optional, only required when modifying package dependencies). [Instructions here](https://github.com/GoogleCloudPlatform/kubernetes#installing-godep)
 
 6. Get the Kubernetes source:
 

hack/config-go.sh

@@ -40,9 +40,9 @@ function gitcommit() {
   return 0
 }
 
-# kube::setup_go_environment will check that `go` and `godep` commands are
-# available in ${PATH}. If not running on Travis, it will also check that the Go
-# version is good enough for the Kubernetes build.
+# kube::setup_go_environment will check that the `go` commands is available in
+# ${PATH}. If not running on Travis, it will also check that the Go version is
+# good enough for the Kubernetes build.
 #
 # Also set ${GOPATH} and environment variables needed by Go.
 kube::setup_go_environment() {
@@ -52,12 +52,6 @@ kube::setup_go_environment() {
     exit 1
   fi
 
-  if [[ -z "$(which godep)" ]]; then
-    echo "Can't find 'godep' in PATH, please fix and retry." >&2
-    echo "See https://github.com/GoogleCloudPlatform/kubernetes#godep-and-dependency-management" >&2
-    exit 1
-  fi
-
   # Travis continuous build uses a head go release that doesn't report
   # a version number, so we skip this check on Travis.  Its unnecessary
   # there anyway.
@@ -72,8 +66,8 @@ kube::setup_go_environment() {
     fi
   fi
 
-  # TODO: get rid of this after PR #1054 gets rid of godep.
-  GOPATH="${KUBE_TARGET}:$(godep path)"
+  # Set GOPATH to point to the tree maintained by `godep`.
+  GOPATH="${KUBE_TARGET}:${KUBE_REPO_ROOT}/Godeps/_workspace"
   export GOPATH
 
   # Unset GOBIN in case it already exsits in the current session.