Moved ci dockerfile under ci folder

Change-Id: I54b031c37c84d2b21db6c2122a086bdf554e42fa
Signed-off-by: Juha Hyttinen <juha.hyttinen@nokia.com>
diff --git a/build/Dockerfile b/ci/Dockerfile
similarity index 100%
rename from build/Dockerfile
rename to ci/Dockerfile