Handle solr < 4.2 .war filename

Prior to 4.2.0, war file contained in solr archive is not named "solr-$version.war" but "apache-solr-$version.war". Using $filename variable should be fine to handle this case since $filename is for now only used to named the tmp directory for uncompression.

This way, old solr versions can be handled by setting $filename_template variable to something like 'apache-solr-<%= @solr_version -%>' when using the solr module.