Revert Java 1.8 changes. Buildable with Java 1.7

There are still active users on Java 1.7, so building with Java 8
was a no-no. This change reverts the recent migration to Java 8,
allowing JDK 1.7 to compile the code.

This means, at least for the time being, no more Lambda expressions
(Boooooooooooooooo!!)

pom.xml

@@ -4,7 +4,7 @@
     <groupId>com.loomcom.symon</groupId>
     <artifactId>symon</artifactId>
     <packaging>jar</packaging>
-    <version>1.2.0</version>
+    <version>1.2.1</version>
     <name>symon</name>
     <url>http://www.loomcom.com/symon</url>
     <properties>
@@ -91,8 +91,8 @@
                 <version>3.1</version>
                 <configuration>
                     <compilerArgument>-Xlint:unchecked</compilerArgument>
-                    <source>1.8</source>
-                    <target>1.8</target>
+                    <source>1.7</source>
+                    <target>1.7</target>
                 </configuration>
             </plugin>