HelenOS switches to Bazaar VCS

After the 0.4.1 release, we abandoned our Subversion repository, leaving all change history behind, and moved on to Bazaar. The new repository is located at bzr://bzr.helenos.org/head and seamlessly continues where HelenOS 0.4.1 stopped. The old repository was made read-only and will stay around for the sake of searching the code history which predates HelenOS 0.4.1. We hope to be able to work more effectively with the new distributed version control system and look forward to the new cooperation possibilities it opens to the new potential developers.