Bug 10231

Restructure code for avoid direct dependencies on Bitbake data store, the QA
framework needs to be implemented in a way to made useful outside Bitbake environment.

There are two kind of Bitbake datastore variables used into the current oeqa codebase,

- Variables used for enable certain helper mechanism like logging, qemu, etc.,
this kind of variables needs to be passed to the classes QemuRunner, etc as arguments instead of call inside d.getVar.
- Variables used by the Test's itself to do/decide certain things, this variables needs to be passed into a directionary to OETestCase class instead of do d.getVar inside, also the OETestCase class needs to have the ability to validate if certain variables was provided.