Merge pull request #380 from mirage/master

mirage-fs and utop updates
sequence 0.3 released
Merge pull request #381 from c-cube/master

Sequence 0.3 released
Add new release of ocaml-rpc
Add compiler constraint on core

This should fix #383
Add homepage for archimedes
Added 'aberto' package
Merge pull request #384 from superbobry/master

Added 'alberto' package
add a snapshot of obuild (no install support yet, but sufficient for mirage)