Fix duplicate proto error in kubectl 1.8.0-alpha.

- Remove vendor'ed package go.pedge.io/pb/go/google/protobuf.
- Update vendor'ed package github.com/libopenstorage/openstorage.

vendor/github.com/libopenstorage/openstorage/api/README.md

@@ -0,0 +1,79 @@
+# OpenStorage API usage
+
+Any storage product that uses the openstorage API can be managed via this API.  Below are some examples of using this API.
+
+### Enumerate nodes in a cluster
+```go
+
+import (
+    ...
+    
+    "github.com/libopenstorage/gossip/types"
+    "github.com/libopenstorage/openstorage/api"
+    "github.com/libopenstorage/openstorage/api/client/cluster"
+)
+
+type myapp struct {
+    manager cluster.Cluster
+}
+
+func (c *myapp) init() {
+    // Choose the default version.
+    // Leave the host blank to use the local UNIX socket, or pass in an IP and a port at which the server is listening on.
+    clnt, err := cluster.NewClusterClient("", cluster.APIVersion)
+    if err != nil {
+        fmt.Printf("Failed to initialize client library: %v\n", err)
+        os.Exit(1)
+    }
+    c.manager = cluster.ClusterManager(clnt)
+}
+
+func (c *myapp) listNodes() {
+    cluster, err := c.manager.Enumerate()
+    if err != nil {
+        cmdError(context, fn, err)
+        return
+    }
+    
+    // cluster is now a hashmap of nodes... do something useful with it:
+    for _, n := range cluster.Nodes {
+    
+     }
+}
+```
+
+### Inspect a volume in a cluster
+```go
+
+import (
+    ...
+    
+    "github.com/libopenstorage/openstorage/api"
+    volumeclient "github.com/libopenstorage/openstorage/api/client/volume"
+    "github.com/libopenstorage/openstorage/volume"
+)
+
+type myapp struct {
+    volDriver volume.VolumeDriver
+}
+
+func (c *myapp) init() {
+    // Choose the default version.
+    // Leave the host blank to use the local UNIX socket, or pass in an IP and a port at which the server is listening on.
+    clnt, err := volumeclient.NewDriverClient("", v.name, volume.APIVersion)
+    if err != nil {
+        fmt.Printf("Failed to initialize client library: %v\n", err)
+        os.Exit(1)
+    }
+    v.volDriver = volumeclient.VolumeDriver(clnt)
+}
+
+func (c *myapp) inspect(id string) {
+    stats, err := v.volDriver.Stats(id, true)
+    if err != nil {
+        return
+    }
+    
+    // stats is an object that has various volume properties and statistics.
+}
+```