Adding the class is needed to separate the exported test
from the test image; both test run under different conditions,
i.e. an exported test doesn't require to change the signal
handling.
This change adds clasess ExportTestContext and ImageTestContext,
both of them inherits from RuntimeTestContext. Also refactors
RuntimeTestContext class, to keep the code common in this class.
Signed-off-by: Mariano Lopez <mariano.lopez@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
