Update layout login view (redo of #6432)

[n9iels]

This is a redo of #6432 because of merge conflicts.
Please see that one for test instructions

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The problem

I discovered that the alignment on the login page of isis is not 100% pixel perfect. The field are just a few pixels to width. Hower, on RTL languages the wrong alignment was very good visible. So this patch solves alignment problems on LTR and RTL languages. I also add the possibility to load the templates-rtl.css in the login-view.
Farther optimizations:

• font-set icon icon-joomla instead of .png icon for the Joomla! logo on bottom of the loginform
• Full width login button

Before/after screenshots

LTR before

LTR after (very small difference on the right of the fields)

RTL before

RTL after

How to test this patch

1. Confirm the before/after screenshots on a LTR language (English)
2. Confirm 100% page width button and sharp Joomla! logo on bottom
3. Change your language to a RTL language (Persion for example)
4. Test step 2 and 3 again.
5. Confirm the login layout is also good shown on mobile devices. Feel free to use the Google Chrome F12 developer tools for this part

Notes

• Also add some extra spaces for CS on some places
• As idea of @dgt41 the login button is full-width. Please let me know how you're thoughts are about that

[wilsonge]

Merging as original PR was already RTC

[n9iels]

Thanks!

[dgrammatiko]

Class btn-block is supposed to equalize the width of the button with the input fields above. Have you tried to clean the browser’s cache?