Added purging of gmf and gmf_set after population of gmf_agg
Removed the obsolete table gmf_data
Fixed a few tests depending on gmf_data
Merge branch 'export-gmf_agg' of github.com:gem/oq-engine into purge-gmf-tables
Merged from master
Merge branch 'export-gmf_agg' into purge-gmf-tables
Removed the dependency on gmf_set from the risk calculator
Fixed indentation
Merge branch 'export-gmf_agg' into purge-gmf-tables
Merge branch 'export-gmf_agg' into purge-gmf-tables
Fixed risk_test.py:EventBasedExportTestCase
Merge branch 'master' of github.com:gem/oq-engine into purge-gmf-tables
Merged from master
calcs/risk/base:

Added a better error message for `check_imts`.
tests/calcs/risk/classical/core_test:

Updated a test (per changes in the code) so that we don't get unicode
artifacts when casting a list to a str.
Merge pull request #1185 from larsbutler/unicode-list-cast-fix

Unicode list cast fix

[r=matley] [f=*trivial]
job/validation:

Fixed a serious logic error in EventBasedRiskForm. The use of []
instead of () in this case makes a difference, and was causing the
logic to be evaluated falsely.
job/validation:

`time_event` is normalized to a string (since in the django model it is
defined as a TextField) and so will never be `None`. Instead, we can
just check for the truth of the field, which will properly handle empty
strings.
job/validation:

Factored out lon/lat validation, which is now shared by 3 different
validator functions. This reduces code duplication and improves code
coverage.
job/validation:

Added missing `time_event_is_valid` function.