[#70172072] refactor runner.main unit tests
[#70172072] refactor: move server into separate package
[#70172072] refactor: move test hooks into ext packages

Signed-off-by: Johannes Petzold <jpetzold@pivotallabs.com>
[#70172072] refactor: eliminate test_helpers & test hook package vars

Signed-off-by: Johannes Petzold <jpetzold@pivotallabs.com>
[#70172072] remove hardcoded bosh paths

Signed-off-by: Johannes Petzold <jpetzold@pivotallabs.com>