Disable non-JDK 8 build profiles.

We use Java 8 specific features now, so we shouldn't bother
with any profiles for compiler settings older than that.

Change-Id: I97b03f76bd7afa66e9be5a20ff64477383525868
Reviewed-on: https://asterix-gerrit.ics.uci.edu/545
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Till Westmann <tillw@apache.org>
Reviewed-by: Chris Hillery <ceej@lambda.nu>
diff --git a/pom.xml b/pom.xml
index 368ba2a..fbe936d 100644
--- a/pom.xml
+++ b/pom.xml
@@ -44,6 +44,7 @@
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <jdk.version>1.8</jdk.version>
         <jvm.extraargs/>
         <!-- Definition of tests in various categories which may be excluded -->
         <hanging.pregelix.tests>**/pregelix/**/FailureRecovery*.java</hanging.pregelix.tests>
@@ -281,24 +282,6 @@
       </build>
     </profile>
     <profile>
-        <id>java6</id>
-        <activation>
-            <jdk>1.6</jdk>
-        </activation>
-         <properties>
-            <jdk.version>1.6</jdk.version>
-         </properties>
-    </profile>
-    <profile>
-        <id>java7</id>
-        <activation>
-            <jdk>1.7</jdk>
-        </activation>
-         <properties>
-            <jdk.version>1.7</jdk.version>
-         </properties>
-    </profile>
-    <profile>
         <id>java8</id>
         <activation>
             <jdk>1.8</jdk>