Added a workload type to handle workloads that have both an APK with an
application and associated automation JAR. Added benchmarkpi
implementation using using the new workload.
- Workload's update_result stage has now been broken up into two parts:
extract_results and update_output. This is to allow the assistant to
pull output from the target in between the two stages.
- Updated assistant implementations for Linux and Android targets from
the exisiting code.
- Extended target descriptor code to handle assistants and their
parameters as well.
- Updated the target manager to actually make use of the assistants.
Changing the way target descriptions work from a static mapping to
something that is dynamically generated and is extensible via plugins.
Also moving core target implementation stuff under "framework".
