cmd/puppeth: format dashboard html, update syncmode flags

* consensus, core, ethstats: use engine specific block beneficiary

* core, eth, les, miner: use explicit beneficiary during mining

* consensus/clique, internal/web3ext: support hash based API queries

* consensus/clique: make RPC return types public

internal/ethapi: Add support for fetching information about the current call in JS traces

- Moved fuse related code in a new package, swarm/fuse
- Added write support
  - Create new files
  - Delete existing files
  - Append to files (with limitations)
- More test coverage

This PR is a prototype implementation of plugable consensus engines and the
Clique PoA protocol ethereum/EIPs#225

eth: announce block after sync cycle (star topology)

* whisper: GetMessages fixed; size restriction updated
* whisper: made PoW and MaxMsgSize customizable
* whisper: test added
* whisper: sym key management changed
* whisper: identity management refactored
* whisper: API refactoring (Post and Filter)
* whisper: big refactoring complete
* whisper: spelling fix
* whisper: variable topic size allowed for a filter
* whisper: final update
* whisper: formatting
* whisper: file exchange introduced in wnode
* whisper: bugfix
* whisper: API updated + new tests
* whisper: statistics updated
* whisper: wnode server updated
* whisper: allowed filtering for variable topic size
* whisper: tests added
* whisper: resolving merge conflicts
* whisper: refactoring (documenting mostly)
* whsiper: tests fixed
* whisper: down cased error messages
* whisper: documenting the API functions
* whisper: logging fixed
* whisper: fixed wnode parameters
* whisper: logs fixed (typos)

travis, appveyor: update to Go 1.8.1

consensus/ethash, eth: don't mine if 0 threads are set

all: clean up various error handling in core and the miner

This PR deprecates the file related RPC calls in favour of an improved HTTP API.

The main aim is to expose a simple to use API which can be consumed by thin
clients (e.g. curl and HTML forms) without the need for complex logic (e.g.
manipulating prefix trie manifests).

* cmd, les, eth, eth/gasprice: using new gas price oracle

* eth/gasprice: renamed source file

* eth/gasprice: added security checks for gpo params

* eth/gasprice: fixed naming issues

* eth/gasprice: max limit, maxEmpty

- intended to be a swarm alternative to termbin.com
- added --stdin flag to swarm executable. if set, swarm will
  read data from stdin and postRaw it.

This commit adds a build step to travis to auto-delete unstable archives older than
14 days (our regular release schedule) from Azure via ci.go purge.

The commit also pulls in the latest Azure storage code, also switching over from
the old import path (github.com/Azure/azure-sdk-for-go) to the new split one
(github.com/Azure/azure-storage-go).

* Makefile: fix devtools target

* core: regenerate genesis marshaling with fjl/gencodec@cbfa5be5a8a8

* core/types: regenerate marshaling methods with fjl/gencodec@cbfa5be5a8a8

* core/types: add "hash" to JSON headers

* debug: Converted uint64-blocknumber into rpc.Blocknumber

* api/debug: Fix pending block issues in DumpBlock

In `touch` operation, only `touched` filed has been changed. Therefore
in the related undo function, only `touched` field should be reverted.
In addition, whether remove this obj from dirty map should depend on
prevDirty flag.

This adds a swarm ls command which lists files and directories stored in a
manifest. Rather than listing all files, it uses "directory prefixes" in case there are a
lot of files in a manifest but you just want to traverse it.

This also includes some refactoring to the tests and the introduction of a
swarm/api/client package to make things easier to test.

This commit adds pluggable consensus engines to go-ethereum. In short, it
introduces a generic consensus interface, and refactors the entire codebase to
use this interface.

ethstats: sanity check ethstats history queries