Add Otter Browser to rapps

Michał Dutkiewicz's Otter Browser works pretty good on ReactOS. There are binaries dedicated for Windows XP and Vista, that have been improved in last weekly releases (it received up-to-date WebKit). It's great choice, mainly because of security reasons (it's hard to receive when using out-of-date browsers). Before 1.0 release, rapps should link to weekly releases, that are as stable as beta release.

• Windows XP binaries are packaged in .zip file, without installer (if it matters).