Add role_invoices

This new role allows users to create invoices without role_finance. Users
can then only modify their own created invoices until somebody with the
role_finance sets the paid_on value.

app/views/finance/invoices/_form.html.haml

@@ -15,7 +15,8 @@
   = f.association :supplier, hint: false
   = f.input :number
   = f.input :date, as: :date_picker
-  = f.input :paid_on, as: :date_picker
+  - if current_user.role_finance?
+    = f.input :paid_on, as: :date_picker
   = f.input :amount, as: :string
   = f.input :deposit, as: :string
   = f.input :deposit_credit, as: :string

app/views/finance/invoices/_invoices.html.haml

@@ -32,6 +32,10 @@
             = ', ' if index > 0
             = link_to format_date(order.ends), new_finance_order_path(order_id: order)
         %td= truncate(invoice.note)
-        %td= link_to t('ui.edit'), edit_finance_invoice_path(invoice), class: 'btn btn-mini'
-        %td= link_to t('ui.delete'), finance_invoice_path(invoice), :data => {:confirm => t('.confirm_delete')}, :method => :delete,
-          class: 'btn btn-danger btn-mini'
+        %td
+          - if invoice.user_can_edit?(current_user)
+            = link_to t('ui.edit'), edit_finance_invoice_path(invoice), class: 'btn btn-mini'
+        %td
+          - if invoice.user_can_edit?(current_user)
+            = link_to t('ui.delete'), finance_invoice_path(invoice), :data => {:confirm => t('.confirm_delete')}, :method => :delete,
+            class: 'btn btn-danger btn-mini'

app/views/finance/invoices/show.html.haml

@@ -47,5 +47,6 @@
   %b= heading_helper(Invoice, :note) + ':'
   =h @invoice.note
 
-= link_to t('ui.edit'), edit_finance_invoice_path(@invoice)
+- if @invoice.user_can_edit?(current_user)
+  = link_to t('ui.edit'), edit_finance_invoice_path(@invoice)
 = link_to t('ui.or_cancel'), finance_invoices_path