[FIX] mail: _fields['type'].selection is a callable

This revert partially the rev. f2e4a10e1a58c932f9a989e642771f5ae75d756a

  File "/home/odoo/src/odoo/8.0/addons/mail/mail_mail.py", line 76, in default_get
      if context and context.get('default_type') and context.get('default_type') not in self._fields['type'].selection:
      TypeError: argument of type 'function' is not iterable
[ADD] ZeroClipboard-based "copy" button on snippets

Also fix ruby setup code, some of its bits were actually Python and didn't
quite work when pasted into irb...
[FIX] allow word wrapping in stripe-style code examples
[FIX] kanban view background is correctly set (web_kanban)

the .oe_background_grey class only changed part of the kanban background
when it was scrolled.  This makes sure that the full table has a grey
background.