CLC-4075 Let Dev and QA both be able to get a Google refresh_token
A recent Signet gem update resulted in non-persisting connections for Dev/QA users
Merge pull request #2978 from raydavis/raywip

CLC-4075 Let Dev and QA both be able to get a Google refresh_token
CLC-4259 - Added Canvas Javascript customizations to link 'Download eGrades' option from Gradebook to LTI tool
CLC-4259 - Implemented LTI configuration for new eGrades Export LTI tool
CLC-4259 - Added AngularJS controller/template for embedded Grade Export LTI application, with CSS styling.
CLC-4259 - Added Canvas::CoursePolicy#can_export_grades? method
CLC-4259 - Added CanvasCourseGradeExportController#download_egrades_csv
CLC-4259 - Added method for cross-origin messaging of parent window to link to new location
CLC-4259 - Updated 'Back to Gradebook' link to send parent window back to Gradebook
CLC-4259 - Added Canvas::CourseUsers#course_grades method to return array of grade hashes
CLC-4259 - Converting Grades array into CSV in CanvasCourseGradeExportController