extend chicken-install functionality

[felix winkelmann]

Stephen Eilert suggested the following:

-update-all: this would update all installed eggs to their newest versions.

-outdated: Instead of blindly updating, you'd be able to check which
eggs are out-of-date

-list [name]: This would query the eggs available, preferably with a
quick summary (similar to the current eggs page). The optional name
argument would allow a filter.

-stale: Got the idea from rubygems. It would basically list the local
eggs with their last atime. Might be helpful for when we reach a
thousand gems ;)

[felix winkelmann]

A plain chicken-install -list has now been implemented in the "experimental" branch [fddf8a7c1].