[Dashboard/Statistics] Fix scans date filter

[skarya22]

Brief summary of changes

• In Study Progression - Scans, the chart would show for each month, but the date registered would only filter for year. So if you do 2017-01-01 to 2017-11-01, a scan at 2017-10 would not show. This has been fixed

Testing instructions (if applicable)

1. Scroll down to Study Progression and switch to Scans in the dashboard
2. Open filters and filter to a specific month and see that it works now