Implemented copy code button feature (alshedivat#1267)

Implemented support for copy code button in code blocks (alshedivat#1262), also updated blog post about code to reflect it.

Author: george-gca

_includes/scripts/misc.html

@@ -12,3 +12,4 @@
 
   <!-- Load Common JS -->
   <script defer src="{{ '/assets/js/common.js' | relative_url }}"></script>
+  <script defer src="{{ '/assets/js/copy_code.js' | relative_url }}" type="text/javascript"></script>

_posts/2015-07-15-code.md

@@ -9,7 +9,37 @@ categories: sample-posts
 This theme implements a built-in Jekyll feature, the use of Rouge, for syntax highlighting.
 It supports more than 100 languages.
 This example is in C++.
-All you have to do is wrap your code in a liquid tag:
+All you have to do is wrap your code in markdown code tags:
+
+````markdown
+```c++
+code code code
+```
+````
+
+```c++
+int main(int argc, char const \*argv[])
+{
+    string myString;
+
+    cout << "input a string: ";
+    getline(cin, myString);
+    int length = myString.length();
+
+    char charArray = new char * [length];
+
+    charArray = myString;
+    for(int i = 0; i < length; ++i){
+        cout << charArray[i] << " ";
+    }
+
+    return 0;
+}
+```
+
+By default, it does not display line numbers. If you want to display line numbers for every code block, you can set `kramdown.syntax_highlighter_opts.block.line_numbers` to true in your `_config.yml` file.
+
+If you want to display line numbers for a specific code block, all you have to do is wrap your code in a liquid tag:
 
 {% raw  %}
 {% highlight c++ linenos %}  <br/> code code code <br/> {% endhighlight %}