[SPARK-5032] [graphx] Remove GraphX MIMA exclude for 1.3

Since GraphX is no longer alpha as of 1.2, MimaExcludes should not exclude GraphX for 1.3

Here are the individual excludes I had to add + the associated commits:

```
            // SPARK-4444
            ProblemFilters.exclude[IncompatibleResultTypeProblem](
              "org.apache.spark.graphx.EdgeRDD.fromEdges"),
            ProblemFilters.exclude[MissingMethodProblem]("org.apache.spark.graphx.EdgeRDD.filter"),
            ProblemFilters.exclude[IncompatibleResultTypeProblem](
              "org.apache.spark.graphx.impl.EdgeRDDImpl.filter"),
```
[apache@9ac2bb1]

```
            // SPARK-3623
            ProblemFilters.exclude[MissingMethodProblem]("org.apache.spark.graphx.Graph.checkpoint")
```
[apache@e895e0c]

```
            // SPARK-4620
            ProblemFilters.exclude[MissingMethodProblem]("org.apache.spark.graphx.Graph.unpersist"),
```
[apache@8817fc7]

CC: rxin

Author: Joseph K. Bradley <[email protected]>

Closes apache#3856 from jkbradley/graphx-mima and squashes the following commits:

1eea2f6 [Joseph K. Bradley] moved cleanup to run-tests
527ccd9 [Joseph K. Bradley] fixed jenkins script to remove ivy2 cache
802e252 [Joseph K. Bradley] Removed GraphX MIMA excludes and added line to clear spark from .m2 dir before Jenkins tests.  This may not work yet...
30f8bb4 [Joseph K. Bradley] added individual mima excludes for graphx
a3fea42 [Joseph K. Bradley] removed graphx mima exclude for 1.3

Author: jkbradley

dev/run-tests

@@ -21,8 +21,10 @@
 FWDIR="$(cd "`dirname $0`"/..; pwd)"
 cd "$FWDIR"
 
-# Remove work directory
+# Clean up work directory and caches
 rm -rf ./work
+rm -rf ~/.ivy2/local/org.apache.spark
+rm -rf ~/.ivy2/cache/org.apache.spark
 
 source "$FWDIR/dev/run-tests-codes.sh"
 

project/MimaExcludes.scala

@@ -36,7 +36,6 @@ object MimaExcludes {
         case v if v.startsWith("1.3") =>
           Seq(
             MimaBuild.excludeSparkPackage("deploy"),
-            MimaBuild.excludeSparkPackage("graphx"),
             // These are needed if checking against the sbt build, since they are part of
             // the maven-generated artifacts in the 1.2 build.
             MimaBuild.excludeSparkPackage("unused"),