MySQL software release : try to make the 'the directory couscous used as download cache does not exist'

MySQL software release : Add egg part so that buildout executes the git clone before looking for cookbook

This reverts commit 01d10d6c. (slapos.reboostrap name was good)

Thanks to using own python with own libraries, there will be library version
conflicts, as lxml is built against own libz.

Thanks to using own python with own libraries, there will be library version
conflicts, as lxml is built against own libz.

It is required to override-update command as section is being update.