Selecting multiple genres in create venue or artist sends only the first value

[ak-seyam]

Expected Behavior :

getting a comma-separated string values when i use request.form['genres']

Actual Behavior:

getting only the first selected genre

Steps to reproduce:

• use the form to add or edit a venue or an artist
• on controller-tier try inspecting request.form['genres'] at '/{artist or venue}/create' route

I know almost nothing about WT Forms and used the solution in #54 to fix the create page but when I saw this line I guessed that the result should be in comma-separated format

[ak-seyam]

you should use form.getlist('key') instead of directly calling the key from the form