Update 2014-03-31-how-to-keep-your-data-consistent-with-foreign-key-constraints.md

This sentence tripped me up: "o if you want to test that 
you cannot accidentally violate your data integrity you could do something 
like this in"

Say something at the end of the first paragraph about "in this post, we'll be going over x" or something like that. 

Maybe something after the first paragraph about how often you / coworkers have to spend hours fixing these issues, etc. Staging stuff!
Merge pull request #2 from venetucci/patch-2

Update 2014-03-31-how-to-keep-your-data-consistent-with-foreign-key-cons...