CMAKE_INSTALL_PREFIX is supposed to be used to set an install prefix
of e.g. /usr or /usr/local. Because we need to install files to /etc,
we had been requiring CMAKE_INSTALL_PREFIX=/ and installing using
relative paths.
The best practice method is to install to /etc using absolute paths,
and then allow CMAKE_INSTALL_PREFIX to set where the final binaries
actually go. Now that it actually has some meaning, the systemd
service is generated to incorporate that path.
Those wishing to use "make install" to install laminar to a subdir
should use "make DESTDIR=path/to/subdir install" and NOT modify
CMAKE_INSTALL_PREFIX.
Documentation and packaging scripts updated accordingly.
The nodes/tags system has not been particularly successful, it's not as
intuitive as it could be, and in an attempt to be a single feature to address
many use cases, ends up addressing none of them particularly well.
This commit replaces nodes and tags with contexts.
Each job may define which context(s) the job may be associated with.
Laminar will only pop the job off the waiting queue when it can be assigned
to a context. A context defines an integer number of executors, which
represents how many runs can be simultaneously assigned to it. A context
may provide extra environment variables.
Essentially, a context replaces a node, and tags are gone. You just assign
jobs to contexts directly, and you can use a glob expression. This should be
more intuitive.
For grouping jobs in the WebUI, a separate mechanism called "groups" is provided.
This helps avoid confusion with the 'docker' directory. Also restore
the debian9 scripts which may be useful for a while longer, update
the names of the scripts and update the README accordingly.
