Lazy evaluation of extractor values for ThymeleafTemplateEngine

[ancho]

I noticed a strange behaviour baking a site using thymeleaf template engine.
https://gitlab.com/devlug/devlug-web

It was awful slow.

08:28:18.835 INFO  org.jbake.app.Oven - Baking finished!
08:28:18.835 INFO  org.jbake.app.Oven - Baked 86 items in 15048ms

I took a look at the memory consumption with visualvm.

When it hits the 500 MB mark the rendering process starts.

With the applied fix the overall bake time goes down do nearly 8 sec.

08:38:40.496 INFO  org.jbake.app.Oven - Baking finished!
08:38:40.496 INFO  org.jbake.app.Oven - Baked 86 items in 7894ms

And the memory consumption looks much better, too.

I had to update the gradle wrapper as bintray dropped TLS 1.0/1.1 support, which caused the java 7 build to fail on travis and appveyor. See https://jfrog.com/knowledge-base/why-am-i-failing-to-work-with-jfrog-saas-service-with-tls-1-0-1-1/

An update to orientdb slipped into this pr. Shall I revert it?

[coveralls]

Coverage decreased (-6.8%) to 73.272% when pulling 8f0ac69 on ancho:feature/fix-thymeleaf-memory-leak into a402b14 on jbake-org:master.

[coveralls]

Coverage decreased (-6.8%) to 73.272% when pulling 8f0ac69 on ancho:feature/fix-thymeleaf-memory-leak into a402b14 on jbake-org:master.

[coveralls]

Coverage decreased (-0.5%) to 80.732% when pulling 44161a7 on ancho:feature/fix-thymeleaf-memory-leak into 4f3a18a on jbake-org:master.

[jonbullock]

Wow that's quite an improvement. The changes looks fine to me and the upgrade to OrientDB is OK too.