Returning from the submit app page without submitting app creates entry in Pending app table

Steps to reproduce the issue:
1) Click on submit your app
2) Select an app to submit from "Choose File" option or Enter URL
3) Go back to the home page or click browser back button without submitting the app

This will create an entry in the pending apps table even if the app is not submitted for the release. Also, this will save the jar file for the app in pending_releases folder in s3 bucket.

Also, if the error page "Something is wrong" is displayed while submitting the app, the app entry will still be created in the AppPending table which can result in improper release of the app without user's approval.