Don't count non-standard answer when calculating wait time mode
added tests for analyze and get_mode
some tests for survey utils
merged develop into this
improved tests coverage of surve/utils.py
fix bug in core/utils/extract_attr and improve test coverage overall
removed comments
improved test coverage
fixed flake8 issues
changed date headers to services/facilities
support hiding generic feedback; exclude all hidden feedback, not only open ended responses
add help_text for GenericFeedback.display_on_dashboard
correct help text for SurveyQuestionResponse and GenericFeedback
Merge pull request #191 from caktus/relabel

changed date headers to services/facilities
Merge pull request #193 from caktus/hide-generic-feedback

support hiding generic feedback; exclude all hidden survey question responses, not only open ended responses
removed placeholder
fix placeholder
fixed placeholders on home page
placeholders
added nigeria