No possible fixVersion exists for CVE-2019-0225

[wtwhite]

The Cue schema requires a non-null value for fixVersion, but none makes sense for CVE-2019-0225. This currently blocks #24.

As the README says:

There is no later version of jspwiki available in the Maven repository that makes these tests
pass as APIs the tests depends on also change. In particular, the required class `org.apache.wiki.auth.TestAuthorizer` needs to implement additional methods 
in `org.apache.wiki.auth.authorize.WebAuthorizer` in `org.apache.jspwiki:jspwiki-main:2.11.0.M7`.  

Also, in 2.11.0 , `WikiEngine` expects that *""JSPWiki requires a container which supports at least version 3.1 of Servlet specification"* and 
enforces this by throwing an exception. However, the mock container provided in `net.sourceforge.stripes:stripes:1.7.0-async-beta`
only supports container version `2.*`. 

Proposed solution: Since we don't actually use fixedVersion in shadedetector, just make it optional in the Cue schema.

[wtwhite]

Fixed in #34.