Break the fs package up into smaller parts.

The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.

The new code layout is documented in CONTRIBUTING.

fs/fshttp/http_new.go

@@ -0,0 +1,33 @@
+// HTTP parts go1.7+
+
+//+build go1.7
+
+package fshttp
+
+import (
+	"context"
+	"net"
+	"net/http"
+	"time"
+
+	"github.com/ncw/rclone/fs"
+)
+
+// dial with context and timeouts
+func dialContextTimeout(ctx context.Context, network, address string, ci *fs.ConfigInfo) (net.Conn, error) {
+	dialer := NewDialer(ci)
+	c, err := dialer.DialContext(ctx, network, address)
+	if err != nil {
+		return c, err
+	}
+	return newTimeoutConn(c, ci.Timeout), nil
+}
+
+// Initialise the http.Transport for go1.7+
+func initTransport(ci *fs.ConfigInfo, t *http.Transport) {
+	t.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
+		return dialContextTimeout(ctx, network, addr, ci)
+	}
+	t.IdleConnTimeout = 60 * time.Second
+	t.ExpectContinueTimeout = ci.ConnectTimeout
+}