updated the screenshots of author (#97)

Multi device mockup screen of blog using https://techsini.com/multi-mockup/

Add default for ALLOW_GOOGLE_FONTS and DEFAULT_LANG (#92)

variable SHOW_MODIFIED_TIME to show modified date in article (#73)

- by default that is false

Add Open Graph support for Linkedin (#64)

* added prefix tag to support Open Graph on Linkedin

* added prefix tag to support Open Graph on Linkedin

linkedin and github link (#27)

* Ref #24 linkedin and github social link in author page and article page

-test case for that

- BaseTest added

* Ref #24 icon to link since linkedin and github is not present

* article color fix

Implement AUTHOR_BIO "name" and "cover" fields. (#16)

* Implement AUTHOR_BIO "name" and "cover" fields.

In the theme readme, there's are "name" and "cover" fields in the
AUTHOR_BIO example, but these two fields weren't implemented yet.

Instead, the author page was displaying the author entry through
the title Jinja2 filter (which doesn't work so well for surnames like
mine, which contains multiple capital letters ;) ), and the cover
image was being used for the avatar image. This change uses the
"name" and "cover" fields for these, respectfully.

The cover image on the author page will also gracefully fall back
to the site default if an author cover isn't specified as well.

* Correct name author name display in post loop

* Set author name if author bio not set

default author name string will be title and that can be override form auther bio name

issues #6 and #7 customize credits

option to enable / disable credits

option to change the credits valus

by default credits is enabled

screenshot added