Add support for nvm use node, nvm use iojs, nvm ls node, and nvm ls iojs

Also add `nvm_version node` and `nvm_version iojs` support.

test/fast/Listing versions/Running "nvm ls node_" should return a nonzero exit code when not found

@@ -2,6 +2,6 @@
 
 . ../../../nvm.sh
 
-nvm ls node
+nvm ls node_
 [ "$?" = "3" ]
 

test/fast/Unit tests/nvm_version

@@ -0,0 +1,47 @@
+#!/bin/sh
+
+die () { echo $@ ; cleanup ; exit 1; }
+cleanup () {
+  unset -f nvm_ls_current nvm_ls
+}
+
+. ../../../nvm.sh
+
+nvm_ls_current() {
+  echo "CURRENT!"
+  return 7
+}
+
+OUTPUT="$(nvm_version current)"
+EXPECTED_OUTPUT="CURRENT!"
+EXIT_CODE="$(nvm_version current 2>&1 >/dev/null ; echo $?)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die '"nvm_version current" did not return nvm_ls_current output'
+[ "_$EXIT_CODE" = "_7" ] || die '"nvm_version current" did not return nvm_ls_current exit code'
+
+OUTPUT="$(nvm_version)"
+EXPECTED_OUTPUT="CURRENT!"
+EXIT_CODE="$(nvm_version 2>&1 >/dev/null ; echo $?)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die '"nvm_version" did not return nvm_ls_current output'
+[ "_$EXIT_CODE" = "_7" ] || die '"nvm_version" did not return nvm_ls_current exit code'
+
+nvm_ls() {
+  echo "line 1"
+  echo "line 2"
+  echo "pattern: $1"
+}
+
+[ "_$(nvm_version foo)" = "_pattern: foo" ] || die '"nvm_version foo" did not pass the pattern to "nvm_ls", or return the last line'
+
+nvm_ls() { echo "N/A"; }
+OUTPUT="$(nvm_version foo)"
+EXPECTED_OUTPUT="N/A"
+EXIT_CODE="$(nvm_version foo 2>&1 >/dev/null ; echo $?)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die '"nvm_version" did not return N/A when nvm_ls returns N/A'
+[ "_$EXIT_CODE" = "_3" ] || die '"nvm_version" returning N/A did not exit code with code 3'
+
+nvm_ls() { echo; }
+OUTPUT="$(nvm_version foo)"
+EXPECTED_OUTPUT="N/A"
+EXIT_CODE="$(nvm_version foo 2>&1 >/dev/null ; echo $?)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die '"nvm_version" did not return N/A when nvm_ls returns nothing'
+[ "_$EXIT_CODE" = "_3" ] || die '"nvm_version" returning N/A did not exit code with code 3'

test/slow/nvm use/Running "nvm use iojs" uses latest io.js version

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+die () { echo $@ ; exit 1; }
+
+. ../../../nvm.sh
+
+nvm deactivate 2>&1 >/dev/null || die 'deactivate failed'
+
+nvm use iojs || die 'nvm use iojs failed'
+OUTPUT="$(nvm current)"
+EXPECTED_OUTPUT="iojs-v1.0.1"
+
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] \
+  || die "'nvm use iojs' + 'nvm current' did not output '$EXPECTED_OUTPUT'; got '$OUTPUT'"

test/slow/nvm use/Running "nvm use node" uses latest stable node version

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+die () { echo $@ ; exit 1; }
+
+. ../../../nvm.sh
+
+nvm deactivate 2>&1 >/dev/null || die 'deactivate failed'
+
+nvm use node || die 'nvm use node failed'
+OUTPUT="$(nvm current)"
+EXPECTED_OUTPUT="$(nvm_version stable)"
+
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] \
+  || die "'nvm use node' + 'nvm current' did not output '$EXPECTED_OUTPUT'; got '$OUTPUT'"

test/slow/nvm use/setup_dir

@@ -0,0 +1,16 @@
+#!/bin/sh
+
+. ../../../nvm.sh
+
+mkdir -p ../../../.nvm_use_bak
+if [ -d "../../../v*" ]; then
+  mv "../../../v*" ../../../.nvm_use_bak/
+fi
+
+for VERSION in "0.8.7" "0.9.1" "0.10.1" "0.11.1"; do
+  nvm install "v$VERSION"
+done
+
+for VERSION in "1.0.0" "1.0.1"; do
+  nvm install "iojs-v$VERSION"
+done

test/slow/nvm use/teardown_dir

@@ -0,0 +1,16 @@
+#!/bin/sh
+
+. ../../../nvm.sh
+
+for VERSION in "0.8.7" "0.9.1" "0.10.1" "0.11.1"; do
+  nvm uninstall "$VERSION"
+done
+
+for VERSION in "1.0.0" "1.0.1"; do
+  nvm uninstall "iojs-v$VERSION"
+done
+
+if [ -d ../../../.nvm_use_bak/* ]; then
+  mv ../../../.nvm_use_bak/* ../../../
+fi
+rmdir ../../../.nvm_use_bak