Replace time journald message for a fixed tail

If the clock of the device is with a wrong data, systemd will not send
the output of 15 minutes ago. journalctl will return that the timestamp is
invalid. Since this patch replaces the use of the time by a fixed number
this problem will not occur anymore.

Signed-off-by: Bruno Bottazzini <bruno.bottazzini@intel.com>

scripts/journalctl-unit.sh

@@ -31,4 +31,4 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 SYSTEMD_UNIT="fbp-runner@$(systemd-escape $1).service"
-journalctl -o json-pretty --since="15 min ago" --no-pager -u "$SYSTEMD_UNIT"
+journalctl -o json-pretty -n 100 --no-pager -u "$SYSTEMD_UNIT"

server/routes.js

@@ -139,7 +139,7 @@
             var child;
             if (!unit_name) {
                 child = spawn('journalctl',
-                                  ['-o', 'json-pretty', '--since=15 min ago', '--no-pager']);
+                                  ['-o', 'json-pretty', '-n', '100', '--no-pager']);
 
                 child.on('error', function(err) {
                     error = true;