[FAB-13292] fix version check in bootstrap.sh

The check for the specified version string should be augmented by wrapping
the command line argument in quotation marks: if no version is provided
(which is allowed), the test fails because the non-quoted variable disappears
and the test bash built-in has two illegal switches next to one another,
leading to

bash: line 181: [: too many arguments

Change-Id: I6ca1d654ef38d6ea0fabcd3ca24c0d861321d489
Signed-off-by: Alessandro Sorniotti <ale.linux@sopit.net>
(cherry picked from commit 56c855d)

Author: ale-linux

scripts/bootstrap.sh

@@ -176,11 +176,11 @@ BINARIES=true
 
 # Parse commandline args pull out
 # version and/or ca-version strings first
-if [ ! -z $1 -a ${1:0:1} != "-" ]; then
+if [ ! -z "$1" -a ${1:0:1} != "-" ]; then
   VERSION=$1;shift
-  if [ ! -z $1  -a ${1:0:1} != "-" ]; then
+  if [ ! -z "$1"  -a ${1:0:1} != "-" ]; then
     CA_VERSION=$1;shift
-    if [ ! -z $1  -a ${1:0:1} != "-" ]; then
+    if [ ! -z "$1"  -a ${1:0:1} != "-" ]; then
       THIRDPARTY_IMAGE_VERSION=$1;shift
     fi
   fi