refactored unit test: test_protocol_decoder.rb renamed test case method names
refactored unit test: test_protocol_decoder.rb
renamed test case method names

test_subscribe_not_implemented -> test_subscribe_dummy
test_unsubscribe_not_implemented -> test_unsubscribe_dummy
test_lsub_not_implemented -> test_lsub_dummy
test_lsub_utf7_mbox_name -> test_lsub_dummy_utf7_mbox_name

y10k/rims