Build and install from GOPATH

* Rename 'vendor/src' -> 'vendor'
  * Ignore vendor/ instead of vendor/src/ for lint
* Rename 'cmd/client' -> 'cmd/ocic' to make it 'go install'able
* Rename 'cmd/server' -> 'cmd/ocid' to make it 'go install'able
* Update Makefile to build and install from GOPATH
* Update tests to locate ocid/ocic in GOPATH/bin
* Search for binaries in GOPATH/bin instead of PATH
* Install tools using `go get -u`, so they are updated on each run

Signed-off-by: Jonathan Yu <jawnsy@redhat.com>

vendor/github.com/opencontainers/runc/libcontainer/user/lookup_unix.go

@@ -0,0 +1,30 @@
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+
+package user
+
+import (
+	"io"
+	"os"
+)
+
+// Unix-specific path to the passwd and group formatted files.
+const (
+	unixPasswdPath = "/etc/passwd"
+	unixGroupPath  = "/etc/group"
+)
+
+func GetPasswdPath() (string, error) {
+	return unixPasswdPath, nil
+}
+
+func GetPasswd() (io.ReadCloser, error) {
+	return os.Open(unixPasswdPath)
+}
+
+func GetGroupPath() (string, error) {
+	return unixGroupPath, nil
+}
+
+func GetGroup() (io.ReadCloser, error) {
+	return os.Open(unixGroupPath)
+}