Update release script

Had an issue where I don't git pull / merge with master after the PR has
been merged.

This adds an option to sync with master before continuing.

script/release.sh

@@ -71,6 +71,7 @@ clone() {
   cd $CLI
   git remote remove origin
   git remote add origin git@github.com:$ORIGIN_REPO/$CLI.git
+  git remote add upstream http://github.com/$UPSTREAM_REPO/$CLI
   git checkout -b release-$1
   cd ..
 }
@@ -134,6 +135,13 @@ git_pull() {
   cd ..
 }
 
+
+git_sync() {
+  cd $CLI
+  git fetch upstream master
+  git rebase upstream/master
+}
+
 push() {
   CHANGES=$(cat changes.txt)
   # Release it!
@@ -217,6 +225,7 @@ main() {
   "Generate changelog"
   "Generate GitHub changelog"
   "Create PR"
+  "Sync with master"
   "Build binaries"
   "Upload the binaries and push to GitHub release page"
   "Clean"
@@ -240,6 +249,9 @@ main() {
           "Create PR")
               git_commit $VERSION
               ;;
+          "Sync with master")
+              git_sync
+              ;;
           "Build binaries")
               build_binaries
               ;;