Decora.jnlp should not use https for homepage

Decora.jnlp uses
  <homepage href="https://scenegraph-effects.dev.java.net/"/>
and this seems to be the only place in FX runtime where https URL is used.

Due to jre bug 6783308 this causes initialization of browser security providers on startup.

This will be eventually fixed in JDK but it is easy to workaround in FX.

Proposed solution:
   Replace https://scenegraph-effects.dev.java.net/ with http://scenegraph-effects.dev.java.net/.
   (http version of url will redirect to https version of url)