Refactor version checking in Joinx. This fixes VcfAnnotate for
v1.10 and provides a basis for centralizing Joinx version checking
as there are other modules that will fail with v1.10 as well.
accept minimum version as argument and drop version module from VcfAnnotate
use version module in Joinx.pm
Merge pull request #285 from ernfrid/joinx_version_check

Refactor version checking in Joinx. This fixes VcfAnnotate for