Replace mockito to mockito2 for newest powermock version
Replace mockito to mockito2 for newest powermock version

It will help to fix mockito class not found exception when running
tests with gradle.

Test: run ./gradlew test, and all tests passed.

Signed-off-by: utzcoz <bf4fcb59289e9979ebf7a02b1609ee526a91bd2d@outlook.com>

farmerbb/Taskbar,farmerbb/Taskbar