Added fixtures for risk tests

Risk QA tests require high resolution hazard data in order to avoid convergency issues.

As it is impractical to compute hazard data before executing the tests (it will take days on a laptop), it is better to store in a dump the test fixture needed to run the tests.

This pull request addresses this problem by 

1) adding the test fixtures in the folder qa_tests/risk/
2) updating the packager.sh script, such that it loads the fixtures before executing the qa tests.

Jenkins build testing this change: http://ci.openquake.org/job/z_oq-engine_template/58/