Improve a bit shell scripts portability.

- Use /bin/sh: bash is not required here;
  - Avoid Perl regexp in grep(1): this is a GNU extension;
  - While here, make ReadNavigo.sh fail earlier if pn53x-tamashell
    fails at first invocation.

Reported by:	Ganael Laplanche <martymac@FreeBSD.org>

examples/pn53x-tamashell-scripts/ReadMobib.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 cat << EOF | \
     pn53x-tamashell |\