Create mounted volumes before running docker

If we mount to a directory the doesn't exist, docker will create the local directory.

If we let docker create the directories, it will create it owned by root-user, and then the container won't be able to write to the directory.
By creating them in-advance, we make them owned by the user, and the container can write to them.
BTW - This solves the problem with 'go build' not being able to write to the 'gocache' directory.

1.8.17: Mount .gitconfig to build container (#109)

This is so that tools inside the container can push code up
to github.

skipper.yaml: Allow type list for environment variables

skipper.yaml spec: enable list type for environment variables

When environment variables are give as list:
  * If a=b, add key a with value b to the docker environment variables.
  * If only a key is given, add it to the docker environment variables if exists in
    the host environment variables.

Allow creating container from non git repositories

Merge pull request #104 from Stratoscale/allow-no-git

Don't fail when not working in a git repository

1.8.11

Tag build container image

1.8.10

Retry on destroy network

1.8.9

Diffuse KEEP_IMAGES environment

1.8.8

Fixed cache image issue, now the cache will point to the latest build…

1.8.7

os environ for keep containers for jenkins usage

1.8.6

Updated README