ignore generated archives
remove zip files and fix archive rake task
remove special test for empty zip
use *.zip extension for test archives
fix class method call
add test for valid package
add one more package test
specify rubyzip version
fix test definition
simplify some exception code
test_package: add some more assertions
support attribute retrieval from definitions and test it
add some more definition methods
restructure definition_test and add new methods
update Gemfile.lock