Make pull request template imperative

Author: samtstern

PULL_REQUEST_TEMPLATE.md

@@ -1,5 +1,5 @@
 Hey there! So you want to contribute to FirebaseUI? Before you file this pull request, follow these steps:
 
-  * Have you read [the contribution guidelines](CONTRIBUTING.md)
-  * Has this been discussed in an issue? If so make sure to mention the issue number here.  If not, go file an issue about this to make sure this is a desirable change.
-  * Are you adding a feature? If so please co-ordinate with someone on [FirebaseUI-iOS](https://github.com/firebase/firebaseui-ios) to make sure that we can implement this on both platforms and maintain feature parity.
+  * Read [the contribution guidelines](CONTRIBUTING.md).
+  * If this has been discussed in an issue, make sure to mention the issue number here.  If not, go file an issue about this to make sure this is a desirable change.
+  * If this is a new feature please co-ordinate with someone on [FirebaseUI-iOS](https://github.com/firebase/firebaseui-ios) to make sure that we can implement this on both platforms and maintain feature parity.