'module' function definition conflict

`riakc_data` defines a function called `module/1`. QuickCheck also exports a function called `module/1`, which gets imported (unqualified) with `-include_lib("eqc/include/eqc.hrl").` This produces either a warning or an error, depending on the version of Erlang:

R16B02:

```
QuickCheck warning: cannot import module/1 because of conflicting definition.
```

R15B01:

```
./rebar eunit skip_deps=true
==> riak-erlang-client (eunit)
src/riakc_datatype.erl:84: defining imported function module/1
ERROR: eunit failed while processing /Users/reid/Documents/repos/basho/riak-erlang-client: rebar_abort
```

cc/ @seancribbs