Added "wait" field in new task and edit task pages

Added UI control to set `wait` option in pa11y script. Updated test
cases.

[pa11y-dashboard issue
#127](https://github.com/springernature/pa11y-dashboard/issues/127)

route/new.js

@@ -42,6 +42,7 @@ function route(app) {
 			standard: req.body.standard,
 			ignore: req.body.ignore || [],
 			timeout: req.body.timeout,
+			wait: req.body.wait,
 			username: req.body.username,
 			password: req.body.password
 		};