[IMP] l10n_es: Complete refactorisation of l10n_es, removing duplicities of the three current charts using charts inheritance. Details of the work done in this blog post (in spanish):

http://serviciosbaeza.com/blog/43-refactorizacion-de-l10n-es-para-openerp-v7
Merge pull request #329 from pedrobaeza/master

[MERGE] l10n_es: Complete refactoring of l10n_es, courtesy of @pedrobaeza

See also:
- https://code.launchpad.net/~pedro.baeza/openobject-addons/7.0-l10n_es-refactorized/+merge/196809
- http://serviciosbaeza.com/blog/43-refactorizacion-de-l10n-es-para-openerp-v7