Multiple fixes

* PDO shell improvements: .query command, -r and --db on command
  line to read commands from file or preselect database.
* Updated build scripts and readme

.spark/build/package.sh

@@ -1,5 +1,10 @@
 #!/bin/bash
 
+if [ ! -f spark.phar ]; then
+    echo "error: No spark.phar has been built yet?"
+    exit 1
+fi
+
 VERSION="$(git describe --tags)"
 PATH="$PWD/tools:$PATH"
 
@@ -16,9 +21,6 @@ echo "  DESTINATION=$DESTINATION"
 echo "* Preparing release direcory"
 mkdir -p $DESTINATION
 
-echo "* Building phar archive"
-pharlite &>/dev/null
-
 echo "* Copying files to release directory"
 cp spark.phar $DESTINATION/spark.phar
 cp README.md $DESTINATION/README.md