Don't load keys when generating keys

Don't display a warning that the `v2_key` does not exist if we are in the process of generating the key.

https://bugzilla.redhat.com/show_bug.cgi?id=1356697

details:

To generate a new appliance encryption key (aka `v2_key`), a user removes and adds a key:

```
mv certs/v2_key certs/v2_key.old
bundle exec ruby tools/fix_auth.rb --key
```

This displays a warning, and looks like it fails but the key is generated:

```
On an appliance, it should be generated on boot by evmserverd.

If you're a developer, you can copy the certs/v2_key.dev to certs/v2_key.

Caution, using the developer key will allow anyone with the public developer key to decrypt the two-way
passwords in your database.
```

Now if the user had not deleted the old `certs/v2_key` then it would throw and error and
 not generate a new `v2_key`. But if you note, it is very hard for the user to know if this is a problem or not:

```
Only generate one encryption_key (v2_key) per installation.
Chances are you did not want to overwrite this file.
If you do this all encrypted secrets in the database will not be readable.
Please backup your key and run again.

tools/fix_auth/fix_auth.rb:50:in `rescue in generate_password': File exists - File exists @ rb_sysopen - certs/v2_key (Errno::EEXIST)
  from tools/fix_auth/fix_auth.rb:42:in `generate_password'
  from tools/fix_auth/fix_auth.rb:90:in `run'
  from tools/fix_auth/cli.rb:37:in `run'
  from tools/fix_auth/cli.rb:41:in `run'
  from ./tools/fix_auth.rb:24:in `<main>'
```

Solution is to not show the warning if in the process of generating the key

tools/fix_auth/fix_auth.rb

@@ -85,7 +85,7 @@ def set_passwords
     end
 
     def run
-      set_passwords
+      set_passwords unless options[:key]
 
       generate_password if options[:key]
       fix_database_yml if options[:databaseyml]