refactor: standardize the HTML, CSS and JSP in the webapps folder.

[jbampton]

Use lowercase HTML tags and attributes.
Add quotes around attributes.
Standardize quotes.
Fix some HTML errors.
Use HTML5 and CSS.
Remove whitespace and blank lines.
Indent HTML and JSP.

[kkolinko]

error.html:

1. Shouldn't it better be <form method="GET"?
2. Options shall be closed with . The
   s there are out of place and ignored. (validator.w3.org complains)

[jbampton]

Hey @kkolinko I removed the br tags and also closed the option tags now.

I also validated the 'error.html' by direct upload and it validates now.

https://validator.w3.org/#validate_by_input

[martin-g]

Why did you remove the auto-closing ? It doesn't do any harm. I, personally, prefer the style it was before.

[jbampton]

In HTML5 you don't need the auto-closing.
I got the style from MDN.
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta

[martin-g]

I know, but it does not do any harm either.
This change makes the diff bigger and harder to back-port to the other branches.
I prefer the XHTML style because it is easier to spot errors in the IDE/text editor without copying to W3C validator in the web.

[jbampton]

error.html:

1. Shouldn't it better be <form method="GET"?
2. Options shall be closed with . The s there are out of place and ignored. (validator.w3.org complains)

MDN says -> Possible (case insensitive) values
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/form

[ChristopherSchultz]

I'm a -1 on this change mostly because it's so large with so many changes at the same time. If this PR had been the accumulation of several commits e.g. (1) re-format whitespace everywhere with no other changes then (2) remove unnecessary auto-close elements then (3) standardize quoting, etc. then it would have been easier to review, spot things we didn't like, etc. But this is one giant change I'm unwilling to read through to decide if I like every single one of them so, no.