Update gems

Follow up for #3612


* Typhoeus: Also running on my pod without apparent issues. Still waiting for feedback from @maxwell  what exactly went wrong. Previous discussion https://github.com/diaspora/diaspora/pull/3568#issuecomment-8584435 Also meanwhile 0.5 came out introducing some possible API changes.
* Webmock: Blocked by Typhoeus
* Markerb: Maybe request a release so we can get rid of pulling it from git?
* Messagebus: Still participation of someone who uses it, and is able to verify it's working after upgrade, needed.
* Capistrano: I'd say ignore for now, find a maintainer and externalize the scripts into another repo.
* Fog: Test if everything releated still works.
* Capybara: major release, lots of changes, basically need to rewrite our integration tests
* XPath: blocked by capbyara
* rack-protection: investigate if their HTTP-Origin plugin would do anything about our `POST /receive` routes
* Carrierwave: Breaking change https://github.com/jnicklas/carrierwave/blob/master/History.txt#L3, investigate if this affects us
* Devise: backward incompatible changes in 2.2 https://github.com/plataformatec/devise/blob/master/CHANGELOG.rdoc
* Fastercsv: Since we're an 1.9 only project it should be possible to drop it.