v0.16.0
Fixing manual install instructions to use the version tag. Relates to #520
Use git in manual install instructions to determine the latest release tag, rather than hardcoding it.

Per https://github.com/creationix/nvm/commit/199ba533403b2a3ad615d0a068a05e59e04e522d
All 4 of these test files should be executable.
Fixing these test files that have never been run
`&>` is a bash-specific extension for redirecting both stdout and stderr.
copy-packages: ensure that `nvm_version` is also applied to compare the provided version to the current one.
install: Ensure that if a version is not provided, we don't try to shift a nonexistent argument.
install: don't output "additional options" when there are none.
Merge pull request #523 from creationix/run_slow_nvmrc_tests_too

Actually run all tests; fix some bugs
Run slow tests in ksh too
Moving actual installation tests to their own suite.
Only run the "installation" tests both with and without curl.
Correct installation test paths
Merge pull request #524 from creationix/run_installation_tests_separately

Run installation tests separately
v0.16.1
Return a nonzero exit code from nvm_rc_version when no .nvmrc found
If there's no "default" specified, fall back to an .nvmrc file.
Unit tests: add `nvm_has`
Unit tests: add `nvm_find_up`