Set JDK and langauge level for entire project.
Set JDK and langauge level for entire project.

To ensure IDEA is configured correctly, set JDK and langauge level for entire
project.

Testing Done:
./gradlew idea
Verified that a freshly created project uses JDK 1.8 with JDK 8 langauge
features.

Reviewed at https://reviews.apache.org/r/40673/

medallia/aurora,crashlytics/aurora,apache/aurora,crashlytics/aurora,apache/aurora,crashlytics/aurora,rdelval/aurora,thinker0/aurora,protochron/aurora,apache/aurora,thinker0/aurora,protochron/aurora,rdelval/aurora,medallia/aurora,apache/aurora,protochron/aurora,apache/aurora,protochron/aurora,rdelval/aurora,thinker0/aurora,thinker0/aurora,rdelval/aurora,rdelval/aurora,protochron/aurora,medallia/aurora,medallia/aurora,thinker0/aurora,crashlytics/aurora,medallia/aurora,medallia/aurora,crashlytics/aurora,apache/aurora,thinker0/aurora,protochron/aurora,rdelval/aurora,crashlytics/aurora