rpcserver/exchanges: Add additional param checks plus other minor bugfixes/improvements (#652)

* deleting the unwanted file created during testing + adding more verbose errors for cli

* wip

* checking params throughout wip

* improving errors

* wip

* thrasher patch

* better err name

* whip

* testing and fixing errors WIP

* upgrades and better errors

* broken test

* wip

* adding some tests

* using tempDir

* mini improvement

* little changes

* better time check

* fixing error

* more glorious changes

* end of day wip

* shazzy changes

* checking error

* appveyor

* last changes:

backtester/config/examples/dca-candles-live.strat

@@ -44,7 +44,7 @@
    "api-secret-override": "",
    "api-client-id-override": "",
    "api-2fa-override": "",
-   "fake-orders": false
+   "real-orders": false
   }
  },
  "portfolio-settings": {