[SPARK-2172] PySpark cannot import mllib modules in YARN-client mode

Include pyspark/mllib python sources as resources in the mllib.jar.
This way they will be included in the final assembly

Author: Szul, Piotr <Piotr.Szul@csiro.au>

Closes #1223 from piotrszul/branch-1.0 and squashes the following commits:

69d5174 [Szul, Piotr] Removed unsed resource directory src/main/resource from mllib pom
f8c52a0 [Szul, Piotr] [SPARK-2172] PySpark cannot import mllib modules in YARN-client mode Include pyspark/mllib python sources as resources in the jar

mllib/pom.xml

@@ -76,5 +76,13 @@
         <artifactId>scalatest-maven-plugin</artifactId>
       </plugin>
     </plugins>
+    <resources>
+      <resource>
+        <directory>../python</directory>
+        <includes>
+          <include>pyspark/mllib/*.py</include>
+        </includes>
+      </resource>
+    </resources>
   </build>
 </project>