Merge pull request #12 from dimagi/rdayalu-analysis

Rdayalu analysis
adding numeric index, with 2010-01-01 as first valid visit (numeric_index = 1)
Merge branch 'rdayalu-analysis' of https://github.com/dimagi/dimagi-data-platform-R into rdayalu-analysis
script to get followup rates by case type for a single domain
moving once-off followup by case type analysis to misc_scripts
Merge pull request #13 from dimagi/rdayalu-analysis

Indicator development
some indicator functions should operate only on visits, not on interactions (of which there may be more than one per visit)
Merge branch 'master' of https://github.com/dimagi/dimagi-data-platform-R into rdayalu-analysis
Modifying indicator calculations for visits vs. interactions