Turn on leveldb developer mode when building devrels

[Vagabond]

I don't know if I did this right, but it seems to work? Without this all the replication tests on giddyup fail because when the 5th or 6th node starts the VM is out of RAM.

cc @jaredmorrow @joedevivo @matthewvon

[joedevivo]

There's an easier way to do this without duplicating code:

{mapping, "leveldb.limited_developer_mem", "eleveldb.limited_developer_mem", [
  {default, true},
  merge
]},

What you're telling the fish is "I've already defined limited_developer_mem, but I just want this one part to override.

This way you don't have to copy the @doc and make sure it stays in sync with the leveldb schema.

[Vagabond]

If I do:

{{#devrel}}
{mapping, "leveldb.limited_developer_mem", "eleveldb.limited_developer_mem", [
  {default, true},
  {level, basic},
  merge
]}.
{{/devrel}}

I get

{mapping, "leveldb.limited_developer_mem", "eleveldb.limited_developer_mem", [
  {default, true},
  {level, basic},
  merge
]}.

Which causes:

ERROR: generate failed while processing /home/andrew/riak/rel: {'EXIT',
    {badarg,
        [{io_lib,format,
             ["Default: ~s",
              [{error,
                   "Tried to convert true, an invalid datatype string to_string."}]],
             [{file,"io_lib.erl"},{line,155}]},
         {cuttlefish_conf,generate_comments,1,
             [{file,"src/cuttlefish_conf.erl"},{line,125}]},
         {cuttlefish_conf,generate_element,1,
             [{file,"src/cuttlefish_conf.erl"},{line,108}]},
         {cuttlefish_conf,'-generate/1-fun-0-',2,
             [{file,"src/cuttlefish_conf.erl"},{line,71}]},
         {lists,foldl,3,[{file,"lists.erl"},{line,1248}]},
         {cuttlefish_conf,generate_file,2,

[joedevivo]

+1, I'll make another PR to make this less repeaty in the future.

[jaredmorrow]

Don't forget to apply this to riak_ee as well.