refactor: remove option normalisation

[achingbrain]

There are just too many options, too many variables and too many different calling contexts so let's get the user to be explicit about how they intend to use the module rather than try to second guess them.

Also, allow the user to specify opts/overrides to the ipfsd server's use of createFactory.

[achingbrain]

I can't say I've come across a lot of any instances where I need one implementation of ipfsModule or ipfsHttpModule in one place and then another somewhere else so it doesn't make a lot of sense to allow them as options to .spawn.

If there's then no danger of sending refs over a http connection maybe we can get rid of the whole path/ref thing and just pass refs in to createFactory?

[achingbrain]

@hugomrdias any changes needed here?

[hugomrdias]

agree lets remove ref/path.

can we remove the second param from findBin also?