clojure package tweaks

[cjlegg]

first draft of a package for clojure has been pushed
it needs:

• a distinction to be made between build and run dependencies (bash and curl may be build only dependencies - problem is how can one be sure?
• permissions for directories - this build script is not a make but a file copy after unzip - what permissions would spack normally set for install directories (there is no similar question for installed files because model build script sets these
• no maintainers specified - I guess this is the norm
• no tests yet (what would they be?)