Date Picker Broken for New Users

**Summary**

When new users are created, if the users do not choose a language setting other than the default language the Language is set to -1. This then causes the date picker to break.

**Steps to Reproduce**

1. site-admin creates a new user
2. When the user logs in for the first time, use the default language
   
3. The Language in the Profile Preferences will be set to -1
   
4. Try editing any issue
5. Add date using date picker
6. An error is displayed : The JIRA Calendar does not currently support your language.
   

**Workaround**

Users needs to

1. Go to Profiles
2. Edit Preferences
3. Click Update
4. The language chosen will be applied