Add tests for tensorflow and lightgbm models

[MischaPanch]

We might also want to update the dependencies as we should support that latest stable versions of those libs

[opcode81]

We can safely update dependencies only if backward compatibility is maintained (no code changes necessary), as otherwise it may break ongoing projects (some of which may not be able to switch to newer versions without a hassle).
What we really need is proper versioning for sensAI... We can switch to newer dependencies with new major versions. (Where needed, we can backport features to older versions.)

[MischaPanch]

I am in the process of adding a script and a bumpversion config that will facilitate releases and versioning. Currently it will support a simple release mechanism by creating tags off develop (I have changed develop to be the default branch) but we can later customize it to our needs.