Add Gemfile and installation instructions

Addresses barryclark#4.

Gemfile

@@ -0,0 +1,8 @@
+source 'https://rubygems.org'
+group :jekyll_plugins do
+    gem 'github-pages'
+    gem 'jekyll'
+    gem 'jekyll-paginate'
+    gem 'jekyll-scholar'
+    gem 'jemoji'
+end

README.md

@@ -16,6 +16,24 @@ The emphasis is on whitespace, transparency, and academic usage: [theme demo](ht
 For more about how to use Jekyll, check out [this tutorial](https://www.taniarascia.com/make-a-static-website-with-jekyll/).
 Why Jekyll? Read this [blog post](https://karpathy.github.io/2014/07/01/switching-to-jekyll/)!
 
+### Installation
+
+Assuming you have [Ruby](https://www.ruby-lang.org/en/downloads/) and [Bundler](https://bundler.io/) installed on your system (*hint: for ease of managing ruby gems, consider using [rbenv](https://github.com/rbenv/rbenv)*), first fork the theme from `github.com:alshedivat/al-folio` to `github.com:<your-username>/<your-repo-name>` and do the following:
+
+```bash
+$ git clone [email protected]:<your-username>/<your-repo-name>.git
+$ cd <your-repo-name>
+$ bundle install
+$ bundle exec jekyll serve
+```
+
+Now, feel free to customize the theme however you like (don't forget to change the name!).
+After you are done, you can deploy it to [GitHub Pages](https://pages.github.com/) by running the deploy script:
+
+```bash
+$ ./bin/deploy
+```
+
 ## Features
 
 #### Ergonomic Publications