Tests speedup by parallel execution of classes in AllTests

Let's speed up the tests by executing their direct classes in suite `org.junit.tests.AllTests` in parallel.
This is the latest junit provider in surefire which has the facility of parallelism.
Since the API of JUnit and TestNG changed in some milestones, the surefire project introduced these providers to handle junit API. Thus these providers are dedicated to junit 3.x, 4.0 and 4.7 or higher. These providers are activated by themselves if you specify `<dependency/>` with JUnit version. Due to JUnit project cannot be dependent on itself of course, I had to specify `surefire-junit47` provider explicitly. This means the plugin's class loader uses this artifact in build phase of our build process only. The surefire project keeps using this junit provider version in the future as well. After `surefire-junit47`, the project decided to switch using junit/testng features by a simple if-else branching in surefire code according to the dependencies section in pom.xml unlike switch providers.