Fix login page after-migration differences

[slaweet]

Expected behaviour

Login should work like before the migration.

Actual behaviour

There are these differences:

• Allows to log in to an offline custom node
• Doesn’t have the “Check for new version” error if API responds with 404
• Some elements are centered instead of left-aligned: Items in network dropdown, error messages on address and passphrase inputs
• Marks URLs with default ports as "Invalid", e.g. http://node03.lisk.io:80 or https://node03.lisk.io:443 Also if the ports are not specified at all.

[slaweet]

This is the old code for “Check for new version” error if API responds with 404:
https://github.com/LiskHQ/lisk-nano/blob/bb27b7470cc739390e6f9744e0e46d705272d9a7/src/services/api/peers.js#L118-L126

And this is the original issue: #309