Russian translation (structure created + some translations)

Added missing files to ru_RU locale, admin.xml, countries.xml,
currencies.xml and languages.xml are translated into Russian, all
missed strings in other files are added from en_US locale.
Partly updated Russian translation
Merge remote-tracking branch 'upstream/ojs-stable-2_4' into ojs-stable-2_4
Upgrading fork from original
Partly updated Russian translation
Russian Translation fully revised
Added Russian locale to all plugins
Merge pull request #55 from ppv1979/ojs-stable-2_4

Fully Revised Russian Translation