Display the CONTENTS of a file from source control within a JIRA issue

I'd like to be able to display the contents of a file from source control (specifically from Stash) directly in a JIRA issue. Bonus points for allowing the authenticated user in JIRA to directly modify the code and commit it back to source control.

The primary use case is for defining requirements using JBehave. Users want the requirements to display directly in JIRA so that developers can see them when writing code to meet the requirements, but the JBehave "code" itself should live in source control somewhere. I'd like the ability to display the contents, NOT just a link, within the JIRA interface. Ideally it would be a custom field that would allow the user to browse to the file in Stash, but if they had to manually enter (copy/paste) the file path, that would be acceptable as well.