R1:d398bcd67c76

Fix argument ordering in error message

Summary:
Before:
```
$ ./config set phabricator.base-uri local.phacility.com:8080
Usage Exception: Config option 'http://' is invalid. The URI must start with https://' or 'phabricator.base-uri'.
```
After:
```
$ ./config set phabricator.base-uri local.phacility.com:8080
Usage Exception: Config option 'phabricator.base-uri' is invalid. The URI must start with http://' or 'https://'.
```

Test Plan: See above

Reviewers: epriestley

Reviewed By: epriestley…