added test for installation with -s option.

test/slow/install from binary

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+set -e
+. ../../nvm.sh
+
+# Remove the stuff we're clobbering.
+[ -e ../../v0.8.6 ] && rm -R ../../v0.8.6
+
+# Install from binary
+nvm install 0.8.6
+
+# Check
+[ -d ../../v0.8.6 ]
+nvm run v0.8.6 --version | grep v0.8.6

test/slow/install from source

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+set -e
+. ../../nvm.sh
+
+# Remove the stuff we're clobbering.
+[ -e ../../v0.8.6 ] && rm -R ../../v0.8.6
+
+# Install from source
+nvm install -s 0.8.6
+
+# Check
+[ -d ../../v0.8.6 ]
+nvm run v0.8.6 --version | grep v0.8.6