Fixes #70

* Parmeterize number of recent posts in index.html

* Replace .Site.Params.recent_posts_number with $.Param "recent_posts_number" in index.html

Fixes #50

Hugo's `.Summary` did not behave as I expected it to, not stripping out
HTML, so I removed the anchor block from around the posts and moved the
links to the image, title and a read more button.

* Adding support for favicon

* Fixing html tag

* add linkedin

* update github svg to fix spacing

* add colors from brandcolors.net

* add github social link

* add github css

* fix css error breaking rollover

Fixes #43

* using Hero sample image in the theme's /static folder
* fall back to site config
* fall back to hard coded default if none set in page or site params

This helps with theme portability.

Also use Site.RegularPages in its default sort, as this is probably what most people want.