initial cut at source built cassandra for #30
align binary build var for C* to use build_url as suffix
bring in ant dependency when building C*
a couple of little fixes with the C* source build, mostly around handling of cassandra_version when source building
handle reading of source version of C* in a way that both 1.2 and 2.0 will work
Merge branch 'feature/cassandra_source_build' into develop