Change src/main/com/github/... to src/main/java/com/github/...

This is the proper folder structure. This patch will also modify
.gitignore to match the recommendations at
https://intellij-support.jetbrains.com/entries/23393067

Add .idea folder, as this is also recommended by the above link.

Change-Id: If5019595acc8ae9f69b0bd8536b72ccf140d4aca
Merge "Change src/main/com/github/... to src/main/java/com/github/..."