We just migrated to Java 1.8. In my personal computer, I installed the JDK 1.8 and make sure that Maven was running fine in using the latest Java version. I'm using a Mac, so when I ran it in Terminal everything worked. However, when I ran it in my IntelliJ IDEA, it said that it was running Java 1.7.
To changed it, go to the following menu: File, Project Structure, then click on Project.
Here is where you can set the SDK for your project. Just change it to the right SDK and that's it.