Revert "Change dependency to Mahout's hadoop-core 0.20.1"

This reverts commit e946eec.

Using Hadoop 0.20 breaks the build completely,
too many class names have changed.

pom.xml

@@ -30,9 +30,9 @@
       <version>1.0.0</version>
     </dependency>
     <dependency>
-      <groupId>org.apache.mahout.hadoop</groupId>
-      <artifactId>hadoop-core</artifactId>
-      <version>0.20.1</version>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-core-with-dependencies</artifactId>
+      <version>0.18.3</version>
     </dependency>
   </dependencies>
   <build>
@@ -59,7 +59,7 @@
       <plugin>
         <groupId>com.theoryinpractise</groupId>
         <artifactId>clojure-maven-plugin</artifactId>
-        <version>1.3.1</version>
+        <version>1.0</version>
         <configuration>
           <sourceDirectories>
             <sourceDirectory>src/main/clojure</sourceDirectory>
@@ -88,6 +88,14 @@
       </extension>
     </extensions>
   </build>
+  <repositories>
+    <repository>
+      <id>stuartsierra-releases</id>
+      <name>Stuart Sierra's personal Maven 2 release repository</name>
+      <url>http://stuartsierra.com/maven2</url>
+      <!-- hadoop-core-with-dependencies 0.18.3 is deployed here. -->
+    </repository>
+  </repositories>
   <distributionManagement>
     <repository>
       <id>stuartsierra-releases</id>