package-release.sh: script breaks if commit msg contains single quote(')

tr doesn't handle single quote properly.
use sed to escape single quote in commit msg

Change-Id: I7bc7a7a8faea0c1de0f677703c640430ec7116f3
Signed-off-by: Jason Hu <jia-cheng.hu@intel.com>
diff --git a/distrib/package-release.sh b/distrib/package-release.sh
index cfdeb1f..a766937 100755
--- a/distrib/package-release.sh
+++ b/distrib/package-release.sh
@@ -165,8 +165,8 @@
     SHA1=$(cd $GIT_DIR && git log --oneline -1 .) || \
         panic "Not a Git directory: $GIT_DIR"
 
-    SHA1=$(printf "%s" "$SHA1" | tr "'" "\\'")
-    eval $VARNAME=\'$SHA1\'
+    SHA1=$(printf "%s" "$SHA1" | sed -e s/\'/\\\'/g)
+    eval $VARNAME=\"$SHA1\"
 }
 
 # Defaults.