Compiling Ignite against different JDKs

[Dood]

Hello all,

I am working on a ticket that is not very difficult, if you are good 
with Idea, Java, Maven etc. I have been a developer in various languages 
but new to Java ;).

I had JDK8 installed and I introduced some changes to the code base that 
cause it to not compile (apparently) against the JDK7. I downloaded JDK7 
and installed it, I went into Project Structure->JDKs in Idea and added 
the version 7 and set it as default for the Ignite project. However, 
every time I try to build the ignite-core module, it complains about 
"invalid source release: 1.8". Clearly I am missing something - but 
what? Are there any instructions anyone can point to for switching JDKs 
in IntelliJ?

Thanks!