Displays the server error modal on HTTP 500 errors

@hippee-lee @tsanko @kevinsproles Changes to display the server error  modal window when there is an HTTP 500 error event on the rootScope.

Please update the TargetProcess story [23810](http://targetprocess/RestUI/Board.aspx?acid=E1D9755C8F06DC3E65078C412790423E#page=userstory/23810&appConfig=eyJhY2lkIjoiMzVCOTE5ODUwMUM0NTE3MzUzQTYxQTRBMUQ4M0UxQTQifQ==) after this is pulled in.