Java Buildpack v2.6

This change updates the Java BUildpack to version 2.6.  Version 2.6
has the following highlights:

* Print OutOfMemory diagnostics to Loggregator (via Troy Astle)
* Support for custom CA certificates when download from a repository
  (via Dave Head-Rapson)
* Tomcat Redis Session Replication support for alternate Redis
  services (via Neil Aitken)
* Improved SSL Diagnostics

Both the online and offline buildpacks are updated as part of this
change.
Merge remote-tracking branch 'origin/pr/570' into develop