WPP-69

- Updating to show error message in UI if encryption error occurs
- Adding catch all error page (mimicing emailplt)
- Updating comment in gateway config to indicate a bean that is not a part of the zimbra example

- Change security class to match EmailPreview's implementation
- Catches when encryption key is at default and logs ERROR message with no stack trace
- Exposes boolean indicating encryption key is at default value
- Uses annotation for bean initialization