Project update

[dkowis]

This initially started by seeing warnings in my source project:

w: Runtime JAR files in the classpath should have the same version. These files were found in the classpath:
    /home/dkowis/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib-jdk8/1.4.10/998caa30623f73223194a8b657abd2baec4880ea/kotlin-stdlib-jdk8-1.4.10.jar (version 1.4)
    /home/dkowis/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-reflect/1.4.10/e2b3c6695eee6085e606d96d685396dce23a3a06/kotlin-reflect-1.4.10.jar (version 1.4)
    /home/dkowis/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib-jdk7/1.4.10/30e46450b0bb3dbf43898d2f461be4a942784780/kotlin-stdlib-jdk7-1.4.10.jar (version 1.4)
    /home/dkowis/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib-jre8/1.1.2/cd6d8b7a32971564fab0846009593f3bfabdcac1/kotlin-stdlib-jre8-1.1.2.jar (version 1.1)
    /home/dkowis/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib-jre7/1.1.2/8fe14858be2d85bb2c8ad1e060f6dafbd45f48f4/kotlin-stdlib-jre7-1.1.2.jar (version 1.1)
    /home/dkowis/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib/1.4.10/ea29e063d2bbe695be13e9d044dcfb0c7add398e/kotlin-stdlib-1.4.10.jar (version 1.4)
    /home/dkowis/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib-common/1.4.10/6229be3465805c99db1142ad75e6c6ddeac0b04c/kotlin-stdlib-common-1.4.10.jar (version 1.4)

It then turned into a bit of a modernization exercise, since the gradle version the project was on is quite old.

So I updated to latest gradle wrapper, which broke some of the kotlin nebula stuff, because now it's natively supported inside gradle. That required updating that stuff, and I ended up touching the tests as well, since they were on an old version of spek.

I opted to go for kotest, as it seems to be popular in the community.