Use io.js instead of node, if available.

ChangeLog

@@ -17,7 +17,7 @@ libsodium is not installed, has been added.
 as i386 and x86_64 code for the iOS simulator.
  - sodium_free() can now be called on regions with PROT_NONE protection.
  - The Javascript tests can run on Ubuntu, where the node binary was
-renamed nodejs.
+renamed nodejs. io.js can also be used instead of node.
 
 * Version 1.0.1
  - DLL_EXPORT was renamed SODIUM_DLL_EXPORT in order to avoid

dist-build/emscripten.sh

@@ -15,7 +15,7 @@ emcc -O3 --closure 1 --llvm-lto 1 $LDFLAGS $JS_EXPORTS_FLAGS \
   "${PREFIX}/lib/libsodium.a" -o "${PREFIX}/lib/libsodium.js" || exit 1
 
 if test "x$NODE" = x; then
-  for candidate in node nodejs; do
+  for candidate in iojs node nodejs; do
     case $($candidate --version 2>&1) in #(
       v*)
         NODE=$candidate