Allow plugins in pending state to be manually deleted

[rnc]

Expected Behavior

If I upload a plugin that is in Pending Approval I should have the ability to delete it (and for bonus, be able to examine the upload to what went wrong)

Current Behavior

I have to manually contact support to find out the issue and potentially delete the upload.

Note that this is similar to #50 but even though that says solved, there is no UI functionality to delete it

[ov7a]

To clarify: currently, it's possible to delete a plugin if it's new and pending approval (the button is located in the profile). However:

1. There's no clear path for removing individual versions pending approval on an existing plugin.
2. Emails can be improved to note that.
3. It should be possible from the plugin page

[rnc]

In my situation I have a plugin that has been released many times but due to the update to the publish-plugin > 1.0 it switched back to pending approval. Its that version I want to examine to see the contents of and to have possibility of removing so I can try uploading again.