def sha_match?(file, gav, use_sha_file=false)
      if File.exists?(file)
        if gav.sha1.nil?
          gav.sha1 = gav_data(gav)['sha1']
        end
        sha(file,use_sha_file) == gav.sha1
      else
        false
      end
    end
def sha_match?(file, gav, use_sha_file=false)
      if File.exists?(file)
        if gav.sha1.nil?
          gav.sha1 = gav_data(gav)['sha1']
        end
        sha(file,use_sha_file) == gav.sha1
      else
        false
      end
    end
sha_match? returns bool by comparing the sha1 of the nexus gav artifact and the local file