task created success message maintained on refresh

[TanyaStere42]

Expected Behavior

1. create task tasks-new.ejs -> tasks.ejs
2. see success message at top of tasks.ejs
3. refresh page
4. no task creation message at the top of tasks.ejs

this applies to both alert alert-success pageSuccessAlert types. QA should address task create and task delete

Current Behavior

1. create task tasks-new.ejs -> tasks.ejs
2. see success message at top of tasks.ejs
3. refresh page
4. note that task creation success message is still there (a jarring experience that implies a task was created a second time)