ckan ksp fake prints exception for future versions

[HebaruSan]

Background

CKAN Version:
421332c

KSP Version:
1.6

Operating System:
Win7

Have you made any manual changes to your GameData folder (i.e., not via CKAN)?
No

Problem

What steps did you take in CKAN?

Ran ckan ksp fake FAKETEST4 fake4 1.6.1 none

See #2627 for background on this command.

What did you expect to happen?

Either create a fake install with 1.6.1 in the readme.txt, or tell me that version 1.6.1 doesn't exist.

What happened instead?

System.ArgumentOutOfRangeException printed (twice).

As in #2640, we don't need a stack trace here, just a short message explaining why "1.6.1" isn't allowed.

And the final line is misleading, because the problem here isn't anything to do with the format.

CKAN error codes (if applicable):

240 [1] ERROR CKAN.CmdLine.KSP (null) - System.ArgumentOutOfRangeException: Your specified version is invalid.
Parameter name: version
   at CKAN.CmdLine.KSP.FakeNewKSPInstall(FakeOptions options)
System.ArgumentOutOfRangeException: Your specified version is invalid.
Parameter name: version
   at CKAN.CmdLine.KSP.FakeNewKSPInstall(FakeOptions options)
Examples for valid version formats: 1.5.0 | 1.5.1 | 1.6.0.2395