Quote cookie values

According to [RFC2019](https://tools.ietf.org/html/rfc2109), this is
required for values containing spaces, and should always be safe for
non-space containing values.

Note that most webservers are quite smart and lenient when parsing
cookie headers. This change however is still useful for servers that
are very strict (such as undertow).

requests/src/requests/Requester.scala

@@ -247,7 +247,7 @@ case class Requester(verb: String,
           connection.setRequestProperty(
             "Cookie",
             allCookies
-              .map{case (k, v) => k + "=" + v}
+              .map{case (k, v) => s"""$k="$v""""}
               .mkString("; ")
           )
         }

requests/test/src/requests/RequestTests.scala

@@ -110,6 +110,14 @@ object RequestTests extends TestSuite{
         val res2 = requests.get("https://httpbin.org/cookies").text().trim
         assert(read(res2) == Obj("cookies" -> Obj()))
       }
+      test("space"){
+        val s = requests.Session(cookieValues = Map("hello" -> "hello, world"))
+        val res1 = s.get("https://httpbin.org/cookies").text().trim
+        assert(read(res1) == Obj("cookies" -> Obj("hello" -> "hello, world")))
+        s.get("https://httpbin.org/cookies/set?freeform=test+test")
+        val res2 = s.get("https://httpbin.org/cookies").text().trim
+        assert(read(res2) == Obj("cookies" -> Obj("freeform" -> "test test", "hello" -> "hello, world")))
+      }
     }
     // Tests fail with 'Request to https://httpbin.org/absolute-redirect/4 failed with status code 404'
     // test("redirects"){