Specify Java version for compiler plugin

In Maven 3 (other versions not checked), building without specifying the Java version gives errors like: "error: generics are not supported in -source 1.3 (use -source 5 or higher to enable generics)". This change fixes the issue.
Set version of maven-compiler-plugin

Also set minimum Maven version to 2.0.9 which was necessary in order to specify latest version of maven-compiler-plugin.
Merge pull request #1 from rehevkor5/patch-1

Specify Java version for compiler plugin