0.07 .gitignore clean-up
0.07 .gitignore clean-up

Clarify how editing, IDE, and build artifacts are to be kept out of the
repository although the build/ directory can be used since anything in
that folder of a clone will be ignored.

apache/incubator-corinthia,apache/incubator-corinthia,apache/incubator-corinthia,apache/incubator-corinthia,apache/incubator-corinthia,apache/incubator-corinthia,apache/incubator-corinthia