Allow ReaderT to work with Fluture

**Is your feature request related to a problem? Please describe.**
It would be nice to be able to use the Fluture async library to work with the ReaderT monad.

**Describe the solution you'd like**
Seamless use the Fluture type.

**Describe alternatives for how you do this now**
I'm using the `Async` type.

**Code**
```js
const C = require('crocks');
const Future = require('fluture');
const {ReaderT} = C;

const ReaderFuture = ReaderT(Future)

ReaderFuture.ask()
.runWith()
.fork(e => e, x => x);
```

This currently results in the following exception:

```bash
/Users/svozza/git/github.com/svozza/crocks-test/node_modules/crocks/Reader/ReaderT.js:23
function () { return (_type + "( " + (Monad.type()) + " )"); }
^

TypeError: Monad.type is not a function
at type (/Users/svozza/git/github.com/svozza/crocks-test/node_modules/crocks/Reader/ReaderT.js:23:49)
at ReaderT (/Users/svozza/git/github.com/svozza/crocks-test/node_modules/crocks/Reader/ReaderT.js:71:29)
at Function.ask (/Users/svozza/git/github.com/svozza/crocks-test/node_modules/crocks/Reader/ReaderT.js:33:14)
at Object. (/Users/svozza/git/github.com/svozza/crocks-test/fluture.js:7:14)
at Module._compile (internal/modules/cjs/loader.js:1085:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)
at Module.load (internal/modules/cjs/loader.js:950:32)
at Function.Module._load (internal/modules/cjs/loader.js:791:14)
at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)
at internal/main/run_main_module.js:17:47
```