Exclude Analytics from head.html include if config token isn't set

[ghost]

https://github.com/knightoftheoldcode/knightoftheoldcode.github.io/blob/master/_includes/head.html#L12

The above code needs to be excluded with liquid if tags if the google_analytics token isn't set in the _config.yml file.

Template:

https://github.com/knightoftheoldcode/knightoftheoldcode.github.io/blob/master/_includes/analytics.html

[ghost]

Also ensure that we are using analytics correctly. Check for proper locations in the resulting structure, etc...

[ghost]

This was just the segment.io code so we will remove it.