HTTPS Repository

Previously, the default repository root pointed at the HTTP endpoint
of download.run.pivotal.io.  This was due to the fact that the HTTPS
certificate (provided by CloudFront) did not match the URI.  The
CloudFront distribution has now been updated with a matching HTTPS
certificate, so this change updates the root to point at the HTTPS
endpoint.

[#77446526]
Merge 77446526-https to master

[#77446526]
Upgrade the default Java Version to 8

With the release of Java 8u20 it is time to move to Java 8. This commit changes
the default Java version that will be used by the Buildpack to '1.8.0_+'.

[#70715740]
Merge branch 'cgfrost-70715740-upgrade-to-java-8'