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 |\

examples/pn53x-tamashell-scripts/ReadNavigo.sh

@@ -1,9 +1,9 @@
-#!/bin/bash
+#!/bin/sh
 
 ID=$(cat << EOF | \
     pn53x-tamashell |\
     grep -A1 "^Tx: 42  01  0b  3f  80" |\
-    grep -o -P "(?<=Rx: 00  ..  ..  )..  ..  ..  .."|sed 's/  //g'
+    sed -e '1d' -e "s/^Rx: 00  ..  ..  \(..  ..  ..  ..\).*/\1/" -e 's/  //g'
 # Timeouts
 3205000002
 # ListTarget ModeB
@@ -13,6 +13,11 @@ ID=$(cat << EOF | \
 EOF
 )
 
+if [ -z "$ID" ]; then
+	echo "Error: I was not abble to read Navigo ID" >&2
+	exit 1
+fi
+
 cat << EOF | \
     pn53x-tamashell |\
     awk '\