swarm: plan bee for content storage and distribution on web3

This change imports the Swarm protocol codebase. Compared to the 'swarm'
branch, a few mostly cosmetic changes had to be made:

* The various redundant log message prefixes are gone.
* All files now have LGPLv3 license headers.
* Minor code changes were needed to please go vet and make the tests
  pass on Windows.
* Further changes were required to adapt to the go-ethereum develop
  branch and its new Go APIs.

Some code has not (yet) been brought over:

* swarm/cmd/bzzhash: will reappear as cmd/bzzhash later
* swarm/cmd/bzzup.sh: will be reimplemented in cmd/bzzup
* swarm/cmd/makegenesis: will reappear somehow
* swarm/examples/album: will move to a separate repository
* swarm/examples/filemanager: ditto
* swarm/examples/files: will not be merged
* swarm/test/*: will not be merged
* swarm/services/swear: will reappear as contracts/swear when needed

swarm/api/http/roundtripper.go

@@ -0,0 +1,69 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package http
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+)
+
+/*
+http roundtripper to register for bzz url scheme
+see https://github.com/ethereum/go-ethereum/issues/2040
+Usage:
+
+import (
+ "github.com/ethereum/go-ethereum/common/httpclient"
+ "github.com/ethereum/go-ethereum/swarm/api/http"
+)
+client := httpclient.New()
+// for (private) swarm proxy running locally
+client.RegisterScheme("bzz", &http.RoundTripper{Port: port})
+client.RegisterScheme("bzzi", &http.RoundTripper{Port: port})
+client.RegisterScheme("bzzr", &http.RoundTripper{Port: port})
+
+The port you give the Roundtripper is the port the swarm proxy is listening on.
+If Host is left empty, localhost is assumed.
+
+Using a public gateway, the above few lines gives you the leanest
+bzz-scheme aware read-only http client. You really only ever need this
+if you need go-native swarm access to bzz addresses, e.g.,
+github.com/ethereum/go-ethereum/common/natspec
+
+*/
+
+type RoundTripper struct {
+	Host string
+	Port string
+}
+
+func (self *RoundTripper) RoundTrip(req *http.Request) (resp *http.Response, err error) {
+	host := self.Host
+	if len(host) == 0 {
+		host = "localhost"
+	}
+	url := fmt.Sprintf("http://%s:%s/%s:/%s/%s", host, self.Port, req.Proto, req.URL.Host, req.URL.Path)
+	glog.V(logger.Info).Infof("roundtripper: proxying request '%s' to '%s'", req.RequestURI, url)
+	reqProxy, err := http.NewRequest(req.Method, url, req.Body)
+	if err != nil {
+		return nil, err
+	}
+	return http.DefaultClient.Do(reqProxy)
+}