Add top_banner functionality

[jerkdavi]

Created front.js file, updated index.html and layout.scss files.
Changes made will be recorded in the Pull Request description of the original popravi.to repository. Likewise, they will be recorded in the commit comment of the forked popravi.to repository.
This commit contains also the changes made by the 44b96ec commit which are not as of yet pulled into the original popravi.to repository.
This addresses issue #34.

This issue was worked on together by next GitHub users
@MihajloVSc
@jerkdavi

changes:

created file front.js

• updated file front.js to contain functions for creating and showing two different versions of 'top_banner' div
• the idea was to be able to hide and show back the banner on click
• the fixmystreet.com site has exclusively the option the close the banner

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updated index.html

• added a script reference to file front.js

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updated layout.scss

• in header class, added justify-content - space-between line
• in menu class, updated position from absolute to relative
• for menu class media, right values updated from 1, -7 to 5, 2.5 respectively
• created top_banner class, and text-aligned - right
• created top_banner p, and text-aligned - center
• created top_banner a, and added text-decoration - underline

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