Add sanity check

[hiker]

While admittedly the documentation contained all the details, when installing this on different machines I ran into some issues that a top level script could pick up early:

• wrong spack version (It requires 0.22, I had 0.21*)
• no libtool installed (resulted in blitz failures, missing lt~obsolete.m4, which is a link to /usr/share/aclocal/lt~obsolete.m4`
• check that gpg agent is running

I also noticed that some unnecessary(?) packages got compiled by spack, e.g. subversion?

Maybe we could trigger the bootstrap script automatically (or combine this), e.g. if no conda, install conda, if no spack, install spack, check spack version and (not sure what to do if the version is wrong ... install correct version??), ...

[hiker]

Given #9 , we should likely also require that a compiler is specified with version number (i.e. not only gcc, but [email protected]).