Update Russian language

Update Russian language file
Update translation
Update subsectionmanager.publish.css

Fix an issue when using a nested Subsection Manager in that the search field didn't having a background making the query hard to read.
Update extension.driver.php

- Use General::deleteFile, General::writeFile for the `subsectionmanager-storage` file
- Put the `subsectionmanager-storage` file in `CACHE`, as that is what it is
Fix uninstaller
Update extension meta data
Image Preview compatibility for Symphony 2.3.3

This probably breaks 2.3.2 compatibility?
Merge pull request #232 from animaux/master

Image Preview compatibility for Symphony 2.3.3
Version 3.1

Symphony 2.3.3 compatibility – this change is not backwards-compatible
Removed file links, Image preview compatibility for Symphony 2.3.3

I guess this breaks 2.3.2 Compatibility?
REALLY make image previews working in 2.3.3

Dirty Hack described here:
http://www.getsymphony.com/discuss/thread/101275/2/#position-24
Merge pull request #230 from alexbirukov/master

Update Russian language
Merge pull request #233 from animaux/master

REALLY make image previews working in 2.3.3, plus file link removal, closes #222
Version 3.1.1
Remove whitespace, add jQuery Migrate
Remove Subsection Tabs
Fix Subsection Manager resizing

Closes #235
Manually merge #231
Update meta information and readme
Don't remove Subsection Tabs tables in the database to make downgrades possible