ctk-schemas uses an expression for version

[david4096]

In the ctk-schemas pom the version field is set using an expression. Maven issues a warning that future versions may not build:

[WARNING] Some problems were encountered while building the effective model for org.ga4gh:ctk-schemas:jar:0.6.0a1
[WARNING] 'version' contains an expression but should be a constant. @ org.ga4gh:ctk-schemas:${ga4gh.schema.local.version}, /Users/david/ga4gh/compliance-david/ctk-schemas/pom.xml, line 20, column 14
[WARNING] 
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING] 
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.