Run all slow tests on all shells
Properly replace the -I curl option for the --server-response wget option.
Apparently wget outputs to stderr, so let's make sure we're checking both stderr and stdout.
Merge pull request #500 from creationix/run_slow_tests_on_all_shells

Run slow tests on all shells
Attempt to improve `nvm copy-packages`
Tests for `nvm copy-packages`