Backporting to beta (#3229)

* Use ethcore_dappsPort when constructing URLs (#3139)

* Upon connect, retrieve the available api ports

* Update dapps to load from dappsPort

* Update dapps summary with dappsPort

* Allow proxy to use dappsPort

* Replace /api/ping with HEAD /

* Dynamic port for available apps

* Retrieve content images with dappsPort

* Fix /

* Transfer token dropdown image fix

* IdentityIcon loads images via contentHash

* Update apps fetch to cater for dev & prod

* DRY up 127.0.0.1:${dappsPort} with ${dappsUrl}

* Cleaning up polluted namespaces (#3143)

* Renaming ethcore_ to parity_

* Renaming files

* Renaming poluted EthSigning

* Tidy up the namespaces

* Renaming files to match new structure

* Splitting EthSigning into separate traits

* jsapi move ethcore.* -> parity.*

* Move jsonrpc parity definitions

* Update UI API calls for parity interfaces

* Move jsapi signer interfaces from personal to signer

* Update UI to use signer.* where applicable

* Updsate jsapi subscriptions for signer

* Fix dodgy merge.

* Update README.

* Fix some tests.

* Move parity-only personal.* to parity.*

* Update UI for personal -> parity API moves

* Update subscription APIs after personal -> parity move

* personal. generateAuthorizationToken -> parity. generateAuthorizationToken (UI)

* enode, dappsPort & signerPort (UI)

* Update subscription tests (accountsInfo)

* subscription update

* personal -> parity

* Additional error logging on method failures

* move postTransaction to parity

* Additional debug info with method failures

* Fix personal tests.

* Console wrning shows parameters, error object does not

* Include parity_ signing methods.

* Console log http transport info

* Fix failing tests

* Add RPC stubs for parity_accounts.

* Allow some secure built-in dapps

* Use parity_accounts in place of accountsInfo

* Improve error reporting

* Cleanup GHH error handling