.gitignore for temp and generated files
Fix jsr305-2.0.2 => 3.0.0 version change

Fixes the following error during the build:
No rule to make target
`$HOME/.m2/repository/com/google/code/findbugs/jsr305/2.0.2/jsr305-2.0.2
.jar', needed by `/PATH/j2objc/java_deps/build_result/jsr305-2.0.2.jar