gedis: proper installer

[zaibon]

currently it seems that we need to read the readme to know what are the dependencies and how to install

Can we make a simple install script or at least have a requirements.txt so we can just pip it ?

[despiegk]

is in the setup.py

[despiegk]

changed readme

there was zdb builder

[Hamdy]

I updated installer to build zdb as well !