Simplify installation of recipe installing scripts
Several software use slapos command and expect this command to have networkcache support enabled, which is achieved in buildout by having slapos.libnetworkcache in the egg "working set" when generating the slapos script.
Introduce a dedicated section to install slapos command and use it in softwares which includes a slapos, testnode and slaprunner. Test softwares like slapos-sr-testing also need a slapos command, but they generate one with development version of slapos.core.
Before these changes, several software were installing slapos indirectly by installing extra-eggs from monitoring stack. The monitoring stack was also modified so that it uses a section with a prefix (monitor-eggs) and users of monitoring stacks were also modified to not use this extra-eggs part from monitoring stack, but install eggs through their own section.
Similar problem also existed with slapos.toolbox, which is installed by several softwares and stacks, for different reasons (because it contains lots of utilities), now that buildout detects parts installing the same path, only one parts can install the scripts. For this, define a section slapos-toolbox that software and stack should install, instead of listing the egg as eggs in a zc.recipe.egg section, because that would install the scripts again.