Merge pull request #2 from rdayalu/master

Pull request for report module folder and files
added report util functions for split-by and monthly aggregate table loading

added try-catch to monthly usage table generation to skip domains with errors
test report
Merge branch 'master' of https://github.com/mloudon/dimagi-data-platform-R
Added library function and generic split-by functions to monthly_usage_report. Created monthly_usage test report to run from start to finish - this test code also creates a function to get rid of the NA problem for confidence intervals. Apply this test structure to all report modules.