Added optional comparision function member for React Table columns data
Example new sorting for Submissions Table Commit Date column
Fixed summeries view (again); added compare_commit_dates function
Added compare functions for group naem and repository name
Addressing hound comment, using !== instead of !=, look for '</a' instead of '<'
Added grace credits sort, moved parse_date out of compare_commit_dates for use by repo table
Fixing merge conflict
compare functions more general
Merge pull request #1906 from toriverly/react-tables-sorting

React tables sorting