PLATFORM-535 Add sanitizer for S3 bucket names in CreateNewWiki

This PR addresses the issue with bucket names and ensures the newly created buckets will have names compatible with both S3 and Swift APIs. The process to create a new bucket name appears only in CreateNewWiki so that place should be sufficient to resolve the issue.

https://wikia-inc.atlassian.net/browse/PLATFORM-535

It is a work in progress.


/cc @Wikia/platform-team @nandy
It's not explicit, but the coding [conventions](http://www.mediawiki.org/wiki/Manual:Coding_conventions/PHP) suggest that branching blocks should be enclosed in braces.