Use JUnit 5 for tests, bump dependencies

cryptography-sc/build.gradle

@@ -13,7 +13,8 @@ uploadArchives {
 dependencies {
     compile project(':core')
     compile 'com.madgag.spongycastle:prov'
-    testCompile 'junit:junit'
     testCompile 'com.nhaarman:mockito-kotlin'
+    testCompile 'org.junit.jupiter:junit-jupiter-api'
+    testRuntime 'org.junit.jupiter:junit-jupiter-engine'
     testCompile project(path: ':core', configuration: 'testArtifacts')
 }