Remove "some-package" already installed message

[starper]

Since build now is trying to install packages before building a module, every time it's called we end up with a lot of "some-package" already installed messages (73 in my case). To be honest, I'm not sure I'm interested in what is already installed even when I call install, but maybe someone is, so it's ok. But seeing this messages every time you call build is a bit irritating.

[f-f]

@starper this should be fixed in #112 (the filtering happens here)

[i-am-the-slime]

Any chance you could make a release with this change in it?

[f-f]

@i-am-the-slime yes, I'll release 0.7 later today :)

[f-f]

@i-am-the-slime 0.7 is now released! 🎉

[i-am-the-slime]

Just tried it. So good, thanks for this great piece of software, Fabrizio!

[f-f]

Thanks for the kind words 🙂