Upgrade to Gradle 5 and Java 10

[klmcc]

Starting with the work done by @vehovsky, I went through and made the changes needed to support Gradle 5. I did this while still using Java 1.8, just to keep things separate. Most of the changes were logical: upgrade gradlew related files, fix things Gradle 5 no longer supported (the closure, instances of left shift). Some of the changes, I'm not sure why they were needed: testng needed an explicit dependency, the test data in CapsuleManifestTest came out in a different (but consistent) order.

Then I looked at Java 10 support. The only problem here was that older versions of Gradle would not work. This was fixed somewhere around version 4.2.X (where X was 2 or 3). So I went into test.sh and cut off every version of Gradle before 4.3. This seemed reasonable to me, but other people may have their reasons for using older versions.

Used with Java 10, there are a number of warnings issued due to Gradle using reflection in a way that is now deprecated. I did not attempt to address those, I think that requires changes to Gradle itself.