Add the ability to override package versions via the UI and add other requirements

Changing title.

In any case, happy birthday!

Thanks! 31, act like 13.

as you'd think the module should determine which version of the package gets installed rather than the user.

Normally, yes. However, there are two use cases where this would be useful.

1) On hosting providers that are stuck on PHP <5.3.3 there may be instances where you have to use a package with a lower requirement. Take Git Wrapper. The library requires some Symfony components that would normally resolve to the 2.2.* version. The problem is that these components require PHP >= 5.3.3, so they potentially wouldn't work on the hosting providers mentioned above. Since Git Wrapper works with versions ~2.0, the user should be able to say "I want to 2.0.*".
2) If a module requires version "1.0.1" of a library and another module requires "1.0.2" of a library, the user should be able to say "use 1.0.1 (or 1.0.2)" without having to patch one of the modules.

Let me know if these don't make sense.
Chris

I thought the idea is Composer resolves that problem

For dependency conflicts, yes, but this is when different modules have different requirements for the same package. Since Composer Manager has to merge the requirements into one, which version does it honor? This is a step before Composer has a crack at it.

Flagging for the 2.x branch.