Export and Import Context Should be Properties Based

The export and import of the context is currently tightly coupled with files.

When the producer phase is finished, we create a file (containing properties), which is then used by the databroker for exporting wherever we want.

The basic Idea is to let the user decide this, and:
* The methods PhasedTestManager.exportPhaseData(), PhasedTestManager.fetchExportFile(), PhasedTestManager. exportContext(File), should all deal with a Properties object
* The methods PhasedTestManager.importPhaseData(), PhasedTestManager.importContext(), should all deal with a Properties object
* The interface PhasedDataBroker should be Properties driven (No ore use of files). This involves both store and fetch
** Deprecate the file ones and create a fetch and a store using a Properties Object.
* Instead of storing the context by files, by default, we will use a, provided databroker that is file driven. When no databroker is set this is used
* importPhaseData(), importContext()