Use async apis (#10)

 - Use async apis instead of sync apis for everything but the S3 download jobs because of aws/aws-sdk-java-v2#953
 - Actually make the `threads` setting work: now we can limit the amount of parallel executions with it
 - Download artifacts after each job has finished and not at the end of all the jobs
 - Moved the helper functions to separate files

Closes #6 #2

Author: derwasp

build.gradle

@@ -74,6 +74,8 @@ dependencies {
     compile 'software.amazon.awssdk:s3:2.5.23'
     compile 'software.amazon.awssdk:codebuild:2.5.23'
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-jdk8:1.2.0-alpha-2'
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.2.0-alpha-2'
 }
 
 task buildJar(type: Jar, dependsOn: classes) {

src/main/kotlin/albelli/junit/synnefo/api/SynnefoOptions.kt

@@ -12,7 +12,7 @@ annotation class SynnefoOptions(
         /**
          * @return the number of parallel threads
          */
-        val threads: Int = 5,
+        val threads: Int = 2,
         /**
          * @return the run level (feature or scenario level)
          */