some features and fixes (#569)

- [x] This pull request adds a feature.
- [x] This pull request fixes certain issues.

- Some very minor changes in css
- Removed prefetch-src CSP since its deprecated and unsupported by any
browser
- Added support for "mailto:" e.g. 'Contact me' menu links.
e.g.:
![image](https://user-images.githubusercontent.com/54581833/118399559-0ad75f80-b65e-11eb-8c45-efdb6e11277c.png)
- Lowered text size of footer on mobile devices.
e.g. before and after:

![image](https://user-images.githubusercontent.com/54581833/118399628-5a1d9000-b65e-11eb-962e-bf21e01a5436.png)

- Defined avatar width and height so content doesn't 'jump' during
page/image loading.
- Added pagination li padding for more easily 'clickable' pagination
links on mobile devices and some other minor changes.
e.g. before and after:

![image](https://user-images.githubusercontent.com/54581833/118399734-db752280-b65e-11eb-9635-527493eee6ad.png)
- Increased size of avatar on mobile devices so it does not look so
small.
e.g. before and after:

![image](https://user-images.githubusercontent.com/54581833/118399760-f2b41000-b65e-11eb-91d4-f4a85656ab5a.png)

- [x] Describe what changes are being made
- [x] Explain why and how the changes were necessary and implemented
respectively

- [x] If you have changed any SCSS code, run `make release` to
regenerate all CSS files

Co-authored-by: Peter Duchnovsky <peter.duchnovsky@erstegroup.com>