Graphx example

fix examples

Author: CrazyJvm <crazyjvm@gmail.com>

Closes #1523 from CrazyJvm/graphx-example and squashes the following commits:

663457a [CrazyJvm] outDegrees does not take parameters
7cfff1d [CrazyJvm] fix example for joinVertices

graphx/src/main/scala/org/apache/spark/graphx/Graph.scala

@@ -344,7 +344,7 @@ abstract class Graph[VD: ClassTag, ED: ClassTag] protected () extends Serializab
    *
    * {{{
    * val rawGraph: Graph[_, _] = Graph.textFile("webgraph")
-   * val outDeg: RDD[(VertexId, Int)] = rawGraph.outDegrees()
+   * val outDeg: RDD[(VertexId, Int)] = rawGraph.outDegrees
    * val graph = rawGraph.outerJoinVertices(outDeg) {
    *   (vid, data, optDeg) => optDeg.getOrElse(0)
    * }

graphx/src/main/scala/org/apache/spark/graphx/GraphOps.scala

@@ -198,10 +198,10 @@ class GraphOps[VD: ClassTag, ED: ClassTag](graph: Graph[VD, ED]) extends Seriali
    *
    * {{{
    * val rawGraph: Graph[Int, Int] = GraphLoader.edgeListFile(sc, "webgraph")
-   *   .mapVertices(v => 0)
-   * val outDeg: RDD[(Int, Int)] = rawGraph.outDegrees
-   * val graph = rawGraph.leftJoinVertices[Int,Int](outDeg,
-   *   (v, deg) => deg )
+   *   .mapVertices((_, _) => 0)
+   * val outDeg = rawGraph.outDegrees
+   * val graph = rawGraph.joinVertices[Int](outDeg)
+   *   ((_, _, outDeg) => outDeg)
    * }}}
    *
    */