Switch to Sinatra::Application from deprecated Sinatra.application
Switch to Sinatra::Application from deprecated Sinatra.application

Signed-off-by: Simon Rozet <088e16a1019277b15d58faf0541e11910eb756f6@rozet.name>

integrity/integrity,faradayio/ci1,factorylabs/integrity,forresty/integrity,faradayio/ci1,dkastner/prism_ci,p/integrity,factorylabs/integrity,forresty/integrity,erik-escobedo/integrity,integrity/integrity,p/integrity,erik-escobedo/integrity,integrity/integrity