Merge pull request #3 from hailocab/upstream-merge

Upstream merge
Add Session wrapper

With this patch we can now use gocqlx like:

```
session.Query(`SELECT * FROM struct_table`, nil).Get(&v)
```

instead of (old format):

```
gocqlx.Query(session.Query(`SELECT * FROM struct_table`), nil).Get(&v)
```

Signed-off-by: Michał Matczuk <michal@scylladb.com>

doc_test.go

@@ -1,9 +1,26 @@
+// Copyright (C) 2017 ScyllaDB
+// Use of this source code is governed by a ALv2-style
+// license that can be found in the LICENSE file.
+
 package gocqlx_test
 
 import (
+	"github.com/gocql/gocql"
 	"github.com/scylladb/gocqlx"
+	"github.com/scylladb/gocqlx/qb"
 )
 
+func ExampleSession() {
+	cluster := gocql.NewCluster("host")
+	session, err := gocqlx.WrapSession(cluster.CreateSession())
+	if err != nil {
+		// handle error
+	}
+
+	builder := qb.Select("foo")
+	session.Query(builder.ToCql())
+}
+
 func ExampleUDT() {
 	// Just add gocqlx.UDT to a type, no need to implement marshalling functions
 	type FullName struct {