Support from-source installs.

Example:

```
nodenv install v0.10.1 --source
```

Fixes #2
Fixes #3
Fixes #4

libexec/nodenv-install

@@ -1,9 +1,11 @@
 #!/usr/bin/env bash
 # Summary: Install a version of NodeJS.
 #
-# Usage: nodenv install <version>
+# Usage: nodenv install <version> [--source]
 #
 # Versions should be in the form of vN.N.N
+#
+# If --source is given, tries to build NodeJS from source.
 
 # Bomb out if we hit an error, ever
 set -e
@@ -15,37 +17,72 @@ set -e
 
 # Pull the desired version out of ARGV
 version="$1"
+version_dir="$NODENV_ROOT/versions/$version"
 
-# Determine OS
-os="darwin"
-
-# Determine arch
-arch="x64"
-
-# URL to download from
-download="http://nodejs.org/dist/${version}/node-${version}-${os}-${arch}.tar.gz"
-
-# Save current PWD 
+# stash the pwd
 OLDPWD=$(pwd)
-version_dir="$NODENV_ROOT/versions/$version"
 
-# Install from bin
+# Are we going to compile this instead?
+compile="$2"
+
+# Make the version dir and get in there
 mkdir -p "$version_dir"
 cd "$version_dir"
 
-# Can't get too clever here
-set +e
+if [ "$compile" = "--source" ]; then
+  # Let's fetch the source and build it
+  download="http://nodejs.org/dist/${version}/node-${version}.tar.gz"
 
-# Download binary tarball and install
-curl -s -f "$download" > /tmp/node-$version.tar.gz && \
-  tar zxf /tmp/node-$version.tar.gz --strip-components 1 || \
-{
-  cd $OLDPWD
-  rmdir "$version_dir"
+  # Can't get too clever here
+  set +e
 
-  echo "nodenv: unable to install NodeJS \`${version}' from binary, download not available"
-  exit 1
-}
+  # Download source and compile it
+  curl -s -f "$download" > /tmp/node-$version.tar.gz && \
+    tar zxf /tmp/node-$version.tar.gz -C /tmp && \
+    cd /tmp/node-$version && \
+    (./configure --prefix="$version_dir" && make && make install) 2>&1 > /tmp/nodenv-install-$version.log && \
+    rm /tmp/node-$version.tar.gz && \
+    rm -rf /tmp/node-$version || \
+    {
+      cd $OLDPWD
+      rm -rf "$version_dir" /tmp/node-$version.tar.gz /tmp/node-$version
+
+      echo "nodenv: installation of $version from source failed" >&2
+      exit 1
+    }
+else
+  # Determine url to download from
+  if [ "$(uname -s)" = "Darwin" ]; then
+    platform="darwin"
+  else
+    platform="$(uname -s)"
+  fi
+
+  if [ "$(uname -m)" = "x86_64" ]; then
+    arch="x64"
+  else
+    arch="$(uname -p)"
+  fi
+
+  # URL to download from
+  download="http://nodejs.org/dist/${version}/node-${version}-${platform}-${arch}.tar.gz"
+
+  # Can't get too clever here
+  set +e
+
+  # Download binary tarball and install
+  curl -s -f "$download" > /tmp/node-$version.tar.gz && \
+    tar zxf /tmp/node-$version.tar.gz --strip-components 1 && \
+    rm /tmp/node-$version.tar.gz || \
+    {
+      cd $OLDPWD
+      rmdir "$version_dir"
+
+      echo "nodenv: unable to install NodeJS \`${version}' from binary, download not available"
+      exit 1
+    }
+fi
 
 echo "Installed ${version}"
 cd $OLDPWD
+