Added a check of consistency of the risk models
Fixed readinput_test.py
Merged from master
Added is_valid_inputs
Removed a duplicated line
Added docstrings per the DamageWriter class
Merge pull request #91 from gem/check-risk-models

Improve the error message when the user sets the wrong calculation_mode
Rename reduce->combine
Fixed an indentation error
Added an .apply method to AccumDict
Fixed a docstring
Merge pull request #93 from gem/DamageWriter

Added a DamageWriter class and the expected outputs for the ScenarioDamage QA tests
Merge branch 'master' of github.com:gem/oq-risklib into scenario_damage_tests