[API] Added IntelliJ EditorAPI and ProjectAPI

Change-Id: I0c0ea3ed112cc14573994eaf739d846fcee445e4
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1799
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
Reviewed-by: Holger Schmeisky <google@schmeisky.com>