List enhancements for the call selector
- list will now hide on blur
- list is now scrollable
workflow is now executable
 - on success a checkmark is shown
 - on error an x is shown
added payload to execution
    * execution now contains payload for sending a body in POST/PUT calls
    * renamed data from execution to formData
apiCall now takes data and type, and switches between payload and formData
Merge remote-tracking branch 'origin/executionPayload' into executionPayload
started with restCallOverviewWidgetSpec
finished  restCallOverviewWidgetSpec
interims commit
* adding rest call overview to have an overview about all available rest calls
* refactored $scope.api to $scope.restCalls
changed .params to .data globally to have it consistent