[FIX] account_analytic_plans: correct call to account_get

The account_get method has the signature
  def account_get(self,... company_id=None, context=None)

so should use positional argument context=context.
Added missing company_id parameter.

Fixes #4084
Merge branch '8.0' of https://github.com/odoo/odoo into 8.0-win32