IDEA-114955 Add support for filtering by regular expressions in Subversion repository view

http://youtrack.jetbrains.com/issue/IDEA-114955

Regex filtering is enabled only when the checkbox is selected.

![regex-filter](https://f.cloud.github.com/assets/5672256/1338149/e5b2e486-35e1-11e3-8843-1d527f2132a3.png)