Add test case and fix test server API for #154

test-server/server.js

 
 app.all('/err-body', (req, res) => {
   res.status(400)
-  res.write({ data : Date.now() })
+  res.write(JSON.stringify({ data : Date.now() }))
   res.end()
 })
 

test/test-0.10.0.js

 //
 // })
 
+describe('#154 Allow passing unparsed response body to error handler ', (report, done) =>{
+
+  RNFetchBlob.fetch('get', `${TEST_SERVER_URL}/err-body`)
+  .then((res) => {
+    console.log(res)
+  })
+  .catch((err) => {
+    console.log(err)
+  })
+
+})
 
 describe('cookie test', (report, done) => {