Failing test for when using nvm ls with v* version
Fix nvm ls for v* numbers

Previously calling nvm ls with v* number (nvm ls v0.2)
would not return any results.

So now the v is prepended if its not already there
Adding an `nvm --version` command
Fix NVM_DIR discovery
When curl is not present, immediately bail out of `nvm install` with a nonzero exit code. Fixes #385.
Merge pull request #374 from koenpunt/fix-tests

 Fix NVM_DIR discovery
Merge pull request #382 from koenpunt/version-normalizing

Fix nvm ls for v* numbers
Add Makefile for multishell testing
updated nvm current test for zsh
install shells before running tests
Merge pull request #386 from koenpunt/multi-shell-test

Add Makefile for multishell testing
Adding a trailing newline
Add travis badge to README
Merge pull request #387 from koenpunt/patch-1

Add travis badge to README
Use NVM_ prefix for variables
Merge pull request #388 from koenpunt/small-fixes

Use NVM_ prefix for non local variables
replaced fatalExit function for 'inline' exit
exit on errors (set -e)
simplified if for NVM_DIR and NVM_SOURCE, corrected indentation
don't make use of pushd and popd as they are not universal
made NVM_DIR and NVM_SOURCE configurable using environment variables
replaced undocumented option for specifying the profile as first argument to specifying it as a environment variable (eg: PROFILE=~/.myprofile ./install-gitless.sh)
also; fixed indentation and added .zshrc as possible profile
Updated source string, use hard path as NVM is not always installed in `$HOME/.nvm`