Remove dependency on Arquillian-BOM pom

Arquillian-BOM should only be imported via DependencyManagement,
and not as a direct Dependency. The idea is to define the versions of Arquillian-Core to use, not to import them all.
Merge pull request #1 from aslakknutsen/patch-3

Remove dependency on Arquillian-BOM pom

Thanks to aslakknutsen for hint