[dmtest] Move the command line parser to its own file
You can now have multiple -t and -n switches.

*** This change requires you to re-run 'bundle' to get the latest ejt_command_line gem ***

The -t switches are ORd together to make one filter.  Similarly the
-n's ORd to make another.  These two are then ANDd to make the final
filter.

eg,

root@debian:~/dmtest# dmtest list --suite thin-provisioning -t /Fake/ -t /Basic/ -n /device\|pass/
thin-provisioning
  BasicTests
    overwrite_a_linear_device
    overwriting_various_thin_devices
    pool_without_thin_devices_does_not_commit
  FakeDiscardTests
    data_granularity_larger_than_block_size_disables_passdown
    data_granularity_not_factor_of_block_size_disables_passdown
    data_max_smaller_than_block_size_disables_passdown
    disable_passdown
    enable_passdown
    pool_max_and_granularity_match_np2_block_size_no_passdown
    pool_max_and_granularity_match_pow2_block_size_no_passdown