Update unit tests, remove need to use new jvm for each test (#308)

• add mockk

• port httpapitest to mockk

• use mockk in internalhttpapitest

• use mockk in mediareceivedstatuschecktest

• use mockk in emptycallstatuschecktest

• use mockk in ffmpegcapturetest

• use mockk in loggingutilskttest

• use mockk in jibrisubprocesstest

• use mockk in processwrappertest

• use mockk in xmppapitest

• remove mockito-kotlin dep

• add utility for mocking/resetting the process output logger

• add helpers to easily mock/reset task pools

• no longer require reuseForks=false

• use mockk.version variable in pom