Gaffer 2.0 Major Release and consequent removal of some old gaffer-tools

[n3101]

Work is underway to create a Gaffer 2.0 major release that will revamp many aspects of Gaffer, introducing breaking changes.

For gaffer-tools 2.0 this means:

1. The gafferpy static python api will go. The alternative fishbowl dynamic api will be completed instead.
2. The abandoned semi-implemented schema builder package will go. If we revisit this idea in future we will just start again with newer tech.
3. The slider package will go. It depends on the retired apache slider and will not work with the more up-to-date versions of hadoop etc that Gaffer is migrating to.

If you care about any of these removals, then please get in touch.