show version of installed maven

command

mvn -v

sample output

Apache Maven 3.0.1 (r1038046; 2010-11-23 04:58:32-0600)
Java version: 1.6.0_11
Java home: C:\java\jdk16\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows xp" version: "5.1" arch: "x86" Family: "windows"