Add fall back login with username and password option to login

[charliescheer]

Fix

We have received some feedback about the new login flow that some people thought we had dropped the login with password option. We have decided to add a button on the login with email page where users can choose to login with email and password instead. This surfaces this option for users who wants it and doesn't require receiving the login email to before you can enter your password. This also helps in circumstances where GAE might be down and login with email isn't possible.

Login	Login with pass

Test

1. Clean install Simplenote
2. On the onboarding page, tap on Sign up. Make sure that you see the username field and the terms and conditions info
3. Go back, tap on Log In.

• confirm that you see the option We'll email you a code to log in, or you can log in manually
• Tap on that and confirm you are shown a login page with username and password fields
• confirm that you can login from that page if you enter both pieces of info

Smoke test the magic links flow and make sure it still looks as expected

Review

(Required) Add instructions for reviewers. For example:

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Release

These changes do not require release notes.

[wpmobilebot]

📲 You can test the changes from this Pull Request in Simplenote Prototype Build by scanning the QR code below to install the corresponding build.

	App Name	Simplenote Prototype Build
	Build Number	pr1656-6909711-0191e9df-f662-4f38-ad06-a765c0809780
	Version	4.53
	Bundle ID	com.codality.NotationalFlow.Alpha
	Commit	6909711
	App Center Build	Simplenote - Installable Builds #375

Automatticians: You can use our internal self-serve MC tool to give yourself access to App Center if needed.

[jleandroperez]

@charliescheer Just one minor note!!

Nice work BTW!!!

Header

1. Launch Simplenote iOS
2. Press on Log In
3. Press on log in manually

As a result, you'll get the header Log in with email failed (...).
We should probably display no header here!

[charliescheer]

@jleandroperez Good call. Dropped the header

[jleandroperez]

Looks great!!