Bug 975108 - Error on git push too generic: An error occurred executing 'gear postreceive'

https://bugzilla.redhat.com/show_bug.cgi?id=975108

The useful `e.message` was only being printed if `--trace` was passed. We now always print the message, which displays something like.

```
remote: An error occurred executing 'gear postreceive' (exit code: 1)
remote: Error message: Failed to execute action hook 'deploy' for 640595622662830496415744 application foobar
remote: 
remote: For more details about the problem, try running the command again with the '--trace' option.
```