[IMP] sale: analytic_account field edition

Now that an analytic account can be linked
to several projects, you might want to change
the analytic on the SO.
Before this commit, the user was allow to create
an analytic account on a confirmed SO but not
modify it. This was usefull when you wanted to
reinvoice an expense on a SO without AA set.
This is now solved (AA is automatically created
when validated expense).
Now, we want to allow set manually the AA before
confirming SO to match the one of potential
projects.

addons/sale/views/sale_views.xml

@@ -384,7 +384,7 @@
                                     <field name="team_id" options="{'no_create': True}"/>
                                     <field name="client_order_ref"/>
                                     <field name="company_id" options="{'no_create': True}" groups="base.group_multi_company"/>
-                                    <field name="analytic_account_id" context="{'default_partner_id':partner_invoice_id, 'default_name':name}" attrs="{'readonly': ['|',('analytic_account_id','!=',False),('invoice_count','!=',0),('state','=','sale')]}" groups="analytic.group_analytic_accounting"/>
+                                    <field name="analytic_account_id" context="{'default_partner_id':partner_invoice_id, 'default_name':name}" attrs="{'readonly': [('invoice_count','!=',0),('state','=','sale')]}" groups="analytic.group_analytic_accounting"/>
                                 </group>
                                 <group name="sale_pay" string="Invoicing">
                                     <field name="date_order" attrs="{'invisible': [('state', 'in', ['sale', 'done', 'cancel'])]}"/>