Exposing Link in the header instead of Links (typicode#394)

- fix the small typo `Links` to `Link`
- update relevant tests

Author: Vahid Panjganj

src/server/router/plural.js

@@ -153,7 +153,7 @@ module.exports = function (db, name) {
     // Slice result
     if (_end || _limit || _page) {
       res.setHeader('X-Total-Count', chain.size())
-      res.setHeader('Access-Control-Expose-Headers', 'X-Total-Count' + (_page ? ', Links' : ''))
+      res.setHeader('Access-Control-Expose-Headers', 'X-Total-Count' + (_page ? ', Link' : ''))
     }
 
     if (_page) {

test/server/plural.js

@@ -261,7 +261,7 @@ describe('Server', function () {
         .get('/list?_page=2')
         .expect('Content-Type', /json/)
         .expect('x-total-count', db.list.length.toString())
-        .expect('Access-Control-Expose-Headers', 'X-Total-Count, Links')
+        .expect('Access-Control-Expose-Headers', 'X-Total-Count, Link')
         .expect(db.list.slice(10, 20))
         .expect(200, done)
     })
@@ -281,7 +281,7 @@ describe('Server', function () {
         .expect('Content-Type', /json/)
         .expect('x-total-count', db.list.length.toString())
         .expect('link', link)
-        .expect('Access-Control-Expose-Headers', 'X-Total-Count, Links')
+        .expect('Access-Control-Expose-Headers', 'X-Total-Count, Link')
         .expect(db.list.slice(1, 2))
         .expect(200, done)
     })