Sidecar Support Added in the Redis Pods

[SuhailRahman]

Fixes #187

Changes proposed on the PR:

• SideCar support functionality added in this PR. Users can add n number of sidecars to the Redis cluster. An example usage is demonstrated below:

apiVersion: databases.spotahome.com/v1
kind: RedisFailover
metadata:
  ....
spec:
  sentinel:
    image: ...
    replicas: 3
  redis:
    image: ...
    replicas: 3
    sidecar:
    - image: docker_image_1
      name: name_1
    - image: docker_image_2
      name: name_2
      .
      .
      .
    - image: docker_image_n
      name: name_n

sidecar also supports port, ImagePullPolicy, and command. For example:

sidecar:
    - image: docker_image_1 // docker image of sidecar
      name: name_1 // name of the sidecar image 
      imagePullPolicy: imagePullPolicy_1 
      port: port_1 // port number of the sidecar container, if this is not mentioned the container takes default port 80
      command: command_1  // command to be executed by the sidecar image when started 

[szelenka]

@ese is there a target for merging this change?

[ese]

Thanks for the PR and sorry for the late response. I think being a generic sidecar It would make sense to have an array of generic V1container instead of custom structure.

[ese]

closed by #435