Compiler Version Fix

`[ERROR] error: Source option 6 is no longer supported. Use 7 or later.`
The build was failing on running "mvn package"

I had to fix it by changing pom.xml to following

```

org.apache.maven.plugins
maven-compiler-plugin
2.3.2

1.7
1.7

```

Please review if this is a good general fix for pom.xml, or any other change is needed else where.