User can update change in enrollment report to view change in enrollment for a time period of their choosing

[crathbun428]

User Story
As a course author, I want to view the change in the enrollees in my course over a period of my choosing, so that I can view enrollment activity over a time period of interest from the course dashboard.

Acceptance Criteria
Scenario: A course author can update the change in enrollment report to view the change in enrollment over a time period of their choosing
Given I am a course author with X permissions
When I view the change in enrollment information in the enrollment section of the course dashboard
Then I can update the default time period to any time period of my choosing
And when I update the time period
Then I see the report update to show me the number of learners enrolled, the number and percentage of learners enrolled broken down by enrollment track (of the tracks available on my instance) update