Chain-selection from UI (#4859)

* First little bits for chain-selection.

* Provide RPCs and get settings through to user defaults.

* Hasty stash.

* Fix updater accidentally redownloading.

* Finish up.

* Add JS tests.

* Hypervisor should never run a binary modified before itself.

* Style.

* Help tweak.

* Fix test compile.

* Fix JS test

* Build fix for tests.

* Revert default chain name

* Another test

* Use spec name via client.

* Fix mock up.

* whitespace

[ci:skip]

* whitespace

[ci:skip]

* remove exit/restart endpoints.

js/src/jsonrpc/interfaces/parity.js

@@ -199,7 +199,7 @@ export default {
         '2017-01-20 18:14:19  Configured for DevelopmentChain using InstantSeal engine',
         '2017-01-20 18:14:19  Operating mode: active',
         '2017-01-20 18:14:19  State DB configuration: fast',
-        '2017-01-20 18:14:19  Starting Parity/v1.6.0-unstable-2ae8b4c-20170120/x86_64-linux-gnu/rustc1.14.0'
+        '2017-01-20 18:14:19  Starting Parity/v1.7.0-unstable-2ae8b4c-20170120/x86_64-linux-gnu/rustc1.14.0'
       ]
     }
   },