[7.0 - fr] Currency Current Rate and base translation

This PR updates the base.pot file which is quite old and fixes two terms which aren't translated in french.

## Description

The translation of the base module haven't been updated since 2013-06-07 as a result, some strings don't properly translate.

"Current Rate" in res.currency list and form view is one example for the french translation

## How to reproduce

* Go on a 7.0 runbot
* Sign in with the base database
* Load a Translation
    * Select French
* Edit your user settings to have french
* Click on OpenERP logo to get company data
    * In configuration, select search more for Devise

## Expected output

There is a column named "Taux Actuel" with french help text

## Actual output

There is a column named "Current Rate" with english help text