Allow comparison of Date Fields

Issue Summary

If a customer attempts to write a JQL that compares to date fields, this JQL is unacceptable by JIRA because it currently unsupported as our expected supports only specific dates in the format YYYY/MM/dd, startofmonth() or durations like "-3w" (refer to the Created section).

Usage Scenario

If a development team would like to compare or measure how many fixes were released before the scheduled due date, it would be great to be able to create a report that compares using JQL:

releasedate < "due date"

Existing Behavior

JIRA would throw an error if you attempt to use the JQL as defined above as it would expect you to use the duration or actual date as described in the summary section.

Expected Behavior

JIRA would allow the user to compare JQL of 2 different date fields.