Create a script to update the version of SPF and generate docs

This change adds a `version.sh` script that updates the version
of SPF and then updates the generated documentation.  Each
update is recorded as a single commit, and when the branch is
merged, the merge commit will be used as the release tag.  This
will mean that tagged releases will included the correct
generated documentation for the version being released.

Progess on #406

bin/version.sh

@@ -0,0 +1,74 @@
+#!/bin/bash
+#
+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Use of this source code is governed by The MIT License.
+# See the LICENSE file for details.
+
+# Script to udpate the version of SPF and generate docs.
+#
+# Author: nicksay@google.com (Alex Nicksay)
+
+# The script must be passed a version.
+if [[ $# < 1 ]]; then
+  echo "Usage: $(basename $0) [<newversion> | major | minor | patch ]"
+  exit 1
+fi
+
+# Change to the root directory.
+cd "$(dirname $(dirname "$0"))"
+
+# Make sure node is properly installed.
+node=$(command -v node)
+npm=$(command -v npm)
+if [[ $node == "" || $npm == "" ]]; then
+  echo "Both node and npm must be installed to update versions."
+  exit 1
+fi
+npm_semver=$(npm list --parseable semver)
+if [[ $npm_semver == "" ]]; then
+  echo 'The "semver" package is needed.  Run "npm install" and try again.'
+  exit 1
+fi
+
+# Validate the version.
+current=$(bin/name.js --version)
+if [[ $1 == "major" || $1 == "minor" || $1 == "patch" ]]; then
+  version=$(`npm bin`/semver -i $1 $current)
+else
+  version=$(`npm bin`/semver $1)
+fi
+if [[ $version == "" ]]; then
+  echo "A valid version is needed."
+  exit 1
+fi
+
+# Validate there are no pending changes.
+if [[ -n $(git status --porcelain) ]]; then
+  echo "Please commit or revert current changes before proceeding."
+  exit 1
+fi
+
+# From here on out, exit immediately on any error.
+set -o errexit
+
+# Save the current branch.
+branch=$(git symbolic-ref --short HEAD)
+
+# Create a version branch, just in case.
+git checkout -b version-$version
+
+# Update package.json
+echo "Updating package.json"
+npm --no-git-tag-version version $version
+echo "Commiting package.json changes..."
+git commit -a -m "Mark v$version for release"
+
+# Update documentatation
+bin/gendocs.sh --head
+echo "Commiting documentation changes..."
+git commit -a -m "Update documentatation for v$version"
+
+echo
+echo "Version has been updated to v$version"
+echo "Please send a pull request with this change."