App: show a banner on startup

Really useful to spot when the JVM started when going through service logs.
Message: @EqualsAndHashCode(callSuper=false)

Otherwise the compiler complains with:

    warning: Generating equals/hashCode implementation but without a call to superclass, even though this class does not extend java.lang.Object. If this is intentional, add '@EqualsAndHashCode(callSuper=false)' to your type.
Merge pull request #38 from airbnb/pierre/banner

App: show a banner on startup, no compilation warning