frontend.py: Add GET method for checking username

[seeeturtle]

This GET method returns rendered status.html. This method requires username as variable.

Closes https://github.com/manu-chroma/username-availability-checker/issues/22

[manu-chroma]

Hey @seeeturtle,

That was quick! But with this PR you handle the following route: /<username>. However, according to the issue, we want to return results for the following route /?username=<username>.

For this you need to make changes at: https://github.com/manu-chroma/username-availability-checker/blob/master/frontend.py#L11. Also, have a look at http://flask.pocoo.org/docs/0.12/quickstart/#routing

From the above link:

To access parameters submitted in the URL (?key=value) you can use the args attribute:

searchword = request.args.get('key', '')```

[manu-chroma]

^ check this too: https://stackoverflow.com/questions/24892035/python-flask-how-to-get-parameters-from-a-url

[manu-chroma]

Since checking for username is the special condition, Can you do if username rather than if not username?

I'm pointing out these things just because you can learn from this. I will merge as soon as you make that change!

[manu-chroma]

^ Now that you've understood the issue and how to fix it, you might want to change commit message to something like: frontend.py: Support username query in GET method? (Since, GET method for that route was already present in the code.)