'Import people' feature enhancement

[mzico]

Experience from 3.1.6:

• User has proper format xlsx spreasheet
• There are duplicate entries
• When we went to upload this xlsx spreadsheet; Gluu Server rejected upload/import due to Duplicate entries. Which is correct.

However, there are opportunities to enhance this feature, such as:

• When there are duplicate UIDs, don't upload/import those entries but don't stop uploading unique entries. That means, duplicate UID entries will be rejected but unique entries will have no issue importing / uploading.
• Show a list of UIDs which are duplicate. It might be some popup or something like that. Don't show the list in 'Red error message' [ upper right corner ] because if I have 50 or 100 duplicate entries.... Error message will be ugly and won't help Gluu Server administration to find out 'which' UIDs are not unique.