Take Redis 5.0 in use

Take Redis 5.0 in use

Modify the dockerfile to use two phase build process. In the first phase
build the redismodules and install them in the second phase. The actual
docker image is built using the publicly available redis docker file
which is using alpine distribution as a base build.

Change-Id: I292c58a61a114b951434bbd26f4798fc1b50d63d
Signed-off-by: Marco Tallskog <marco.tallskog@nokia.com>