[ENH]: Change uid and gid permissions on bucket creation

[asreimer]

As per #13, on some systems, the UID and GID of user directories on the host are not the same as the default in the resen-core image. This PR executes /usr/local/bin/start.sh with the NB_UID and NB_GID environment variables set.

The side effect of doing this is that it takes a little while for all of the files in /home/jovyan to change permissions, but this will get better once EarthCubeInGeo/resen-core#19 is implemented.

To test this, just create a new bucket. Then in jupyterlab, open terminal and execute the top command. You will probably see a chmod command running, unless you happen to have the same uid and gid as is default for the jovyan user in the container.

Please merged PR #27 before merging this one.

[ljlamarche]

When I try to select start jupyterlab at the end of create_bucket, it gives me an error that the bucket is not running.

[resen] >>> create_bucket test3
Please choose a version of resen-core. Available versions: 2019.1.0rc1
>>> Select a version: 2019.1.0rc1
>>> Mount storage to /home/jovyan/work? (y/n): n
>>> Mount additional storage to /home/jovyan/mount? (y/n): n
>>> Start bucket and jupyterlab? (y/n): y
Creating bucket with name: test3
...adding core...
...adding mounts...
Bucket created successfully!
...starting jupyterlab...
ERROR: Bucket test3 is not running!

The bucket status is listed as None.

[resen] >>> status
Bucket Name         Docker Image             Status                   
test3               2019.1.0rc1              None                     

However, if I try to start the bucket, I get an error that the bucket is already running.

[resen] >>> start_bucket test3
ERROR: Bucket test3 is already running!

I didn't have any of these issues when I was testing PR #27 .

[pmreyes2]

1. ERROR: Bucket test3 is not running!
   happens because the container has been started inside DockerHelper.create_container and the following is missing:

self.buckets[ind]['docker']['status'] = 'running'
self.save_config()

2. The /usr/local/bin/start.sh should be executed with detach=False for the chowns to finish before starting jupyter. If the jupyter notebook is started before this process, the notebook with the token doesn't work.
3. A suggestion would be to put the execution of /usr/local/bin/start.sh inside DockerHelper.start_container. I have tested that and it works. Its in the branch: fix_uid_gid. I could to a PR to merge that into enh_guided_create_bucket
4. Unfortunately it takes long to chown all the files both in linux and mac. But in mac is not needed. If we find a way to know what systems need this fix. Maybe something like docker0.info()['OSType'] == 'linux'. But I don't know if all linux systems need this.

[asreimer]

Not touching this until after 2019.1.0rc2 is out. Low priority.