tests/calcs/hazard/classical/post_processing_test:

Cleaned up a bunch of post processing tests. These removed tests exercise some
code which will be removed shortly.
calcs/hazard/classical/post_processing:

Removed a bunch of obsolete post processing code.

One code, two code, red code, NUKE CODE!!!
calcs/hazard:

Moved `do_aggregate_post_proc` to the base hazard calculator (so it can be
used by the Event-Based hazard calc.

Cleaned up imports a bit as well.
shapes:

Removed some unused imports.
calcs/hazard/classical/post_processing:

Removed the unused function `setup_tasks`.
db/models:

Removed some more unused code.
tests/calcs/hazard/classical/core_test:

Removed an obsolete test.
tests/db/models_manager_test:

Removed obsolete tests for the HazardCurveDataManager.
tests/calcs/hazard/classical/post_processing_test:

Decimal inputs for `test_weighted_quantile_with_decimal_weights` are now
constructed from strings, to more closely match the calculator code.

Also added another comment to better explain what the test case is doing.
tests/utils/helpers:

Removed `skipit`.
Merge pull request #1088 from larsbutler/post-proc-cleanup

Hazard post-processing code cleanup

[r=micheles,matley] [f=*1082312]