Add libfii-dev in README (need for weezyprint)

Use unique serial for hardware

README.md

@@ -50,7 +50,7 @@ Install dependencies. On Debian, you will probably need the
 `python-dev`, `python-pip`, `libldap-dev`, `libpq-dev`, `libsasl2-dev`,
 and `libjpeg-dev` packages.
 
-    sudo apt-get install python-dev python-pip libldap2-dev libpq-dev libsasl2-dev libjpeg-dev libxml2-dev libxslt1-dev
+    sudo apt-get install python-dev python-pip libldap2-dev libpq-dev libsasl2-dev libjpeg-dev libxml2-dev libxslt1-dev libffi-dev
 
 You need a recent *pip* for the installation of dependencies to work. If you
 don't meet that requirement (Ubuntu trusty does not), run:

hardware_provisioning/migrations/0013_auto_20161110_2246.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('hardware_provisioning', '0012_auto_20161110_2225'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='item',
+            name='serial',
+            field=models.CharField(help_text='ou toute autre r\xe9f\xe9rence unique)', unique=True, max_length=250, verbose_name='N\xb0 de s\xe9rie', blank=True),
+            preserve_default=True,
+        ),
+    ]

hardware_provisioning/models.py

@@ -45,7 +45,7 @@ class Item(models.Model):
         help_text="préférable au n° de série si possible")
     serial = models.CharField(
         verbose_name='N° de série',
-        max_length=250, blank=True,
+        max_length=250, blank=True, unique=True,
         help_text='ou toute autre référence unique)')
     buy_date = models.DateField(verbose_name='date d’achat')
     owner = models.ForeignKey(