(!!) Removes support for Node 5.x due to v8 bugs (#47)

v8 4.6.85.x (Node 5.x) has a bug in the optimiser where an invocation of Object.defineProperty passing the result of Object.getOwnPropertyDescriptor in Core.ADT's `extend` function ends up evaluating the latter to undefined in the absence of other side-effects.

See #47 for more details.

.travis.yml

@@ -1,5 +1,4 @@
 language: node_js
 node_js:
   - "4"
-  - "5"
   - "6"

README.md

@@ -33,7 +33,7 @@ Folktale can be installed through [npm][]:
 
 ## Supported platforms
 
-  - Node 4+
+  - Node 4.x, Node 6+ ([**Node 5.x is not supported**](https://github.com/origamitower/folktale/issues/47))
 
 **Browsers**:
   - Chrome 23+

test/specs-src/core.adt.js

@@ -10,7 +10,7 @@
 //
 //----------------------------------------------------------------------
 
-const { property, forall} = require('jsverify');
+const { property } = require('jsverify');
 const {data, setoid, show, serialize} = require('folktale/core/adt')
 
 describe('Core.ADT', () => {
@@ -130,12 +130,10 @@ describe('Core.ADT', () => {
       // NOTE: this fails randomly in Node 5's v8. Seems to be a v8
       // optimisation bug, although I haven't had the time to analyse
       // it yet.
-      /*
       property('Gets a tag with the same name as the constructor', 'string', (a) => {
         const adt = data('', { [a](){ return {} }});
         return adt[a]()[data.tagSymbol] === a;
       });
-      */
 
       property('Gets a hasInstance method that only looks at type/tag', 'string', (a) => {
         const b = a + '2';