Adjust options for sorting information products

[alanorth]

OpenRXV currently sorts information products by "issue date". It would be nice to be able to sort by "accession date" (dc.date.accessioned).

Also, update the text of the drop-down menu to be more clear to non-technical users:

• Date of publication
• Date added to repository
• Type of output
• First author
• Altmetric attention score
• Repository views & downloads

[moayadnajd]

@alanorth please review

[alanorth]

I see the sort options available now. Thank you. It seems that a few are not working:

• Date added to repository
• Type of output
• First author (though actually I don't know if this is even feasible due to mixing of author name formats)

[alanorth]

Working great. Thanks!