Tips:
To check what Java Version you have:
1. Go to Terminal
2. Copy + Paste the following "/usr/libexec/java_home -V"
3. Hit Enter
4. You should see all the Java Versions you have available to you
5. If it says, for example "jdk1.8.0_31", then use that version in the file search code above ;D
This was a step I took before I got mine working. Enjoy!
EDIT: I have done some thorough testing with multiple versions, and the Mod accepts basically all 1.8 Forge versions, so you do not need a specified version.