Use custom PR template by default

                    
|Q            |A   |
|---          |--- |
|Bug Fix?     |no  |
|New Feature? |Y   |
|BC Breaks?   |no  |
|Deprecations?|no  |
|Tests Pass?  |Y   |
|Fixed Tickets|#266|
|License      |MIT |
                    

Use the custom PR table by default if it is defined in the .gush.yml file
 Sent using [Gush](https://github.com/gushphp/gush)
@pierredup this is the bug, we are assuming config is set at all times at this stage in the decoration of commands when it isn't. Trying to think how to solve this.