Internationalization and partial localization

Adds support for Russian, French and Slovenian languages.
By Andrew Kaplanov. https://reviews.apache.org/r/8916

git-svn-id: https://svn.apache.org/repos/asf/incubator/wave/trunk@1437989 13f79535-47bb-0310-9956-ffa450edef68
Added translation to Spanish

https://reviews.apache.org/r/9159/

git-svn-id: https://svn.apache.org/repos/asf/incubator/wave/trunk@1440462 13f79535-47bb-0310-9956-ffa450edef68
Added title to output buttons

Review: https://reviews.apache.org/r/9289/

git-svn-id: https://svn.apache.org/repos/asf/incubator/wave/trunk@1442205 13f79535-47bb-0310-9956-ffa450edef68