Spanish translation

Enrique G. Paredes sent a spanish translation (attached) along with a list of cosmetic problems brought by it (below). Moreover, he also sent a translated example file. The task here is:

• Integrate the translations in the project and with Transifex.
• Add a mechanism to open a localized example file
• Fix, if reasonable, the list of problems below.

Mac OS X
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- All the Sparkle framework localizations are missing (and also please update it to the last version, since some "msgids" seem to have changed)
- Dialogs too narrow (maybe should be sized after the maximum length of the localized strings):
  * Preferences   
  * CSV import options
- Localization not loaded:
  * Export CSV dialog:
     cocoa/ui/export_panel.py [6]: scopeRadio = RadioButtons(result, ["All", "Selected"])
  * Date range selector text:
     cocoa/mg_cocoa.py ?
     qt/controller/date_range_selector.py ?

Windows
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- Localization not loaded in the "Update" dialog:
  * Title: "Checking for updates"
  * Message: "Your software is up to date"
- Localization not loaded in the "About moneyGuru":
  * Title: "About moneyGuru"
  * Button: "OK" "Register"

All
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- Names of the months are not translated (in charts, DateRangeSelector, etc…)
- There are some not escaped '&' chars in gettext strings, I've found: 
  * core/gui/account_pie_chart.py [64]:  _AccountPieChart.__init__(self, networth_view, tr('Assets && Liabilities'))
  * core/gui/main_window.py [47]:  PaneType.Profit: tr("Profit && Loss"),
  * core/gui/profit_graph.py [42]:   return tr('Profit && Loss')
  * qt/controller/main_window.py [193]:   self.actionShowProfitLoss = QAction(tr("Profit && Loss"), self)
  * You can check other possible failures by running:
    grep -R -e "tr(.* && .*)" . # Missing escaped &
    grep -R -e " & .*\")" .  # Mac OS X conflictive cases?