Add bStats metrics.

Metrics will greatly help the development process in terms of finding out which server versions people are running, as well as which features they are using. For now, we check to see how widespread Vault is, and how many arenas and classes people have.

Advanced bar charts are, at the time of this commit, not supported in the bStats dashboard. When they are supported again, we can look into usage statistics for specific settings and features.

pom.xml

@@ -31,6 +31,30 @@
           <finalName>MobArena</finalName>
         </configuration>
       </plugin>
+
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-shade-plugin</artifactId>
+        <version>3.1.0</version>
+        <configuration>
+          <createDependencyReducedPom>false</createDependencyReducedPom>
+          <minimizeJar>true</minimizeJar>
+          <relocations>
+            <relocation>
+              <pattern>org.bstats</pattern>
+              <shadedPattern>com.garbagemule.MobArena.metrics</shadedPattern>
+            </relocation>
+          </relocations>
+        </configuration>
+        <executions>
+          <execution>
+            <phase>package</phase>
+            <goals>
+              <goal>shade</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
 
     <resources>
@@ -54,6 +78,11 @@
       <id>vault-repo</id>
       <url>http://nexus.hc.to/content/repositories/pub_releases</url>
     </repository>
+
+    <repository>
+      <id>bstats-repo</id>
+      <url>http://repo.bstats.org/content/repositories/releases/</url>
+    </repository>
   </repositories>
 
   <dependencies>
@@ -73,6 +102,13 @@
       <scope>provided</scope>
     </dependency>
 
+    <dependency>
+      <groupId>org.bstats</groupId>
+      <artifactId>bstats-bukkit</artifactId>
+      <version>1.2</version>
+      <scope>compile</scope>
+    </dependency>
+
     <!-- Magic Spells (tentative) -->
     <dependency>
       <groupId>com.nisovin</groupId>