* Create rolling releases using the Gitlab API.
This commit builds rolling releases of Container images using the latest commit
on master branch if the pipeline passed for it. The script which gets the
references is still un-tested and should be tested.
The latest commit hashes are passed as arguments to the Dockerfile, which is
then used by PIP to install the specific version of the dependency.
The default value of SECRET_KEY was hard-coded in the settings.py which would turn out to be used all the time even if people are not forced to change it. So this commit removes that value and instead gets the SECRET_KEY from the environment variable.
Closes#99
