Changes

Upgrade Ivy to 2.5.2

The current version (2.4.0) was released in December 2015. Since
then three releases have been made including CVE fixes and some
features. Ivy 2.5+ requires Java 8 as the minimum version and
includes new features like the ability to depend on timestamped
SNAPSHOTs.
See https://ant.apache.org/ivy/history/2.5.0/release-notes.html,
https://ant.apache.org/ivy/history/2.5.1/release-notes.html and
and https://ant.apache.org/ivy/history/2.5.2/release-notes.html
for the list of associated changes