BUG silence info-messages from sub-commands in non-verbose mode
ENH hashdist.core.cache: basic generic key-value-cache on disk
DiskCache: add a memory cache layer
DiskCache: invalidate() method
BUG invalidate() on empty cache
BUG *turns red*
DiskCache: on_disk flag to put()
links: supports multiple glob patterns in "select"
recipes: successful use of DebianPackage + change dep resolution

Changed dependency resolution to always bring in total dependencies
(for now)
change hashes to 160-bit base32 (closes #20)
DOC point tutorial to 'stable' branch