Added test for nvm unload

test/fast/Running "nvm unload" should unset all function and variables.

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+fail () { echo $@ ; exit 1; }
+
+. ../../nvm.sh
+
+type nvm > /dev/null 2>&1 || fail "NVM not loaded"
+
+nvm unload
+
+type nvm > /dev/null 2>&1 && fail "NVM not unloaded" || exit 0