Lowercase username for FreeDNS

[justinthomas]

As per the FreeDNS API, usernames must be lowercase before determining the SHA string. As such, this PR converts the username to lowercase first.

Login Screen (username contains uppercase letter):

Current Behavior:

Succeeds with proposed change:

I tested by uploading the modified file to the home directory of my existing instance and ran it from there. I did not start an entirely new setup via Google Cloud.

[Navid200]

@justinthomas Doesn't FreeDNS change your userID to all lowercase anyway?

I just submitted a request to create a new account and chose an ID containing a capital letter.
In the activation email, the userID is all lower case.
When I log in, I see my user ID is all lower case.

Can you log into FreeDNS and look on the main page at the top right (see the second image on this page: https://navid200.github.io/xDrip/docs/Nightscout/FreeDNS.html). Does it not show your user ID all lower case?
That is what the users have been asked to enter as their user ID in the guide, what is shown on that page.

Therefore, I don't believe this PR is required.
Of course I understand that someone may not know that FreeDNS changed their user ID to all lowercase. But, I don't think this is the solution. Their effective user ID has no capital letters. This PR hides this fact from them.

I am happy to modify the guide to make this more pronounced. Please have a look at the guide and suggest to me how you think it would be more clear that the user must use the user ID as shown on the main page of FreeDNS.

[Navid200]

@justinthomas I think what we should do instead is to add a dialog to inform the user that they should log into FreeDNS and take note of their user ID. I will open a PR to do that.

[justinthomas]

Ahh, the perils of a password manager. I saved the username I generated, not the one FreeDNS told me I had.

You are correct that the emailed and displayed username is lowercase. I'll close this PR and review your new one instead.

Thanks for all of your hard work on this, by the way!

[Navid200]

@justinthomas Thanks for opening this PR. I had never paid attention to what had happened. The fact is that I chose a user ID with a capital letter. But, I never realized that it had been converted.
So, I would have completely missed this issue if you had not raised it here.
Thanks so much for paying attention and opening this PR.