Automatically update dependent packages when publishing

[onigoetz]

Hi @guigrpa,

This PR addresses the issues mentioned in #100 opened by @jeroenptrs

What it does :

• When a package is dirty, all packages that depend on it (recursively) get flagged as dirty as well
• Once a version is chosen, it will update the version in all packages including the dependencies.

What this PR could do better:
This current implementation is a naive approach to open the discussion, it could be improved by

• Only updating the version if it's not in range
• Allow to specify to set dependencies in ranges (^) instead of exact versions

What do you think ?

[coveralls]

Coverage decreased (-0.03%) to 80.28% when pulling 983ac29 on onigoetz:master into 693e599 on guigrpa:master.

[guigrpa]

I've finally implemented it myself, using oao bump internally (it implements the same behaviour, actually). Thanks for the effort and ideas in #100 (which have been credited in the changelog).

[onigoetz]

Cool, you're welcome :) I didn't need my code to be included, ideas are more important than code :)

I inspired myself from the bump command, didn't think of just importing it though ^^