Fleetautoscaler: Add check to have minReplicas>0 when use percents bufferSize

[aLekSer]

When n% is used for bufferSize, Fleet would have 0 Replicas forever if minReplicas set to 0 and no
GameServers were allocated. Currently we are calculating number of
GS in a fleet based on Allocated count.

[agones-bot]

Build Succeeded 👏

Build Id: 4e17e574-8578-4dea-a4a0-8d1e2d3e9986

The following development artifacts have been built, and will exist for the next 30 days:

• image: gcr.io/agones-images/agones-controller:0.11.0-9dc6f30
• image: gcr.io/agones-images/agones-sdk:0.11.0-9dc6f30
• image: gcr.io/agones-images/agones-ping:0.11.0-9dc6f30
• Linux C++ SDK (build): agonessdk-0.11.0-9dc6f30-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-0.11.0-9dc6f30.zip

A preview of the website (the last 30 builds are retained):

• https://9dc6f30-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/GoogleCloudPlatform/agones.git pull/795/head:pr_795 && git checkout pr_795
• helm install install/helm/agones --namespace agones-system --name agones --set agones.image.tag=0.11.0-9dc6f30

[markmandel]

LGTM! 🔬

[agones-bot]

Build Succeeded 👏

Build Id: 3aeafb07-59cb-4110-9e17-678899899bcf

The following development artifacts have been built, and will exist for the next 30 days:

• image: gcr.io/agones-images/agones-controller:0.11.0-118e063
• image: gcr.io/agones-images/agones-sdk:0.11.0-118e063
• image: gcr.io/agones-images/agones-ping:0.11.0-118e063
• Linux C++ SDK (build): agonessdk-0.11.0-118e063-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-0.11.0-118e063.zip

A preview of the website (the last 30 builds are retained):

• https://118e063-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/GoogleCloudPlatform/agones.git pull/795/head:pr_795 && git checkout pr_795
• helm install install/helm/agones --namespace agones-system --name agones --set agones.image.tag=0.11.0-118e063