Issue with Python 2.6

[cbertelli]

Hello,
thanks for the plugin, I think it's very useful for any public body who has to verify compliance with regulations or zoning. Anyway, it doesn't run under python 2.6.
It's a zero effort fix. Just add a zero here:
localePath = os.path.join(self.plugin_dir, 'i18n', 'constraintchecker_{0}.qm'.format(locale))