Added a parser for GMF scenario
Merge pull request #85 from gem/1160398

Importing GMF in XML format: step 1, parsing
allow multi hazardcurves. added example
added writer and more tests
Merge branch 'master' of https://github.com/gem/oq-nrmllib into hazard-curve-multi
Added an assert_valid function to nrmllib
Merge pull request #87 from gem/1167324

Add an assert_valid function to nrmllib
Merge pull request #86 from matley/hazard-curve-multi

Hazard curve in multiple IMTs
Extended the use of assert_valid
Merge pull request #88 from gem/assert_valid

Remove the duplication between assert_valid and assert_is_valid
remove bounds
Merge pull request #89 from gem/remove-bounds-from-loss-ratio

Remove upper bound limit for loss ratio in the vulnerability model and loss curve schema
add nonstco
tests improved
Merge pull request #91 from matley/nonstco

Added non-structural cost attributes and elements
hazard/writers:

Added `SourceModelXMLWriter`. It still needs documentation, though.
hazard/parsers:

Fixed a comment.
tests/hazard/writers_test:

Added `SourceModelXMLWriterTestCase`.
tests/hazard/writers_test:

PEP8 whitespace fix.
hazard/writers:

Added missing docstrings to `SourceModelXMLWriter`.