Add support for configure destination directory of Maven

[frodoslaw]

Add support for configure installation directory of Maven, insted of hardcoded /opt.

That includes: exec maven-untar:

exec { 'maven-untar':
      command => "tar xf /tmp/apache-maven-${version}-bin.tar.gz",
      cwd     => '/opt',
      creates => "/opt/apache-maven-${version}",
      path    => ['/bin','/usr/bin'],
    }