makefile should check installed version of go

[whyrusleeping]

@chriscool could you put this together? You already did it nicely for gx versions, and reusing that code would be great.

[chriscool]

Ok, I will take a look soon.

[chriscool]

By the way should we just test that go version is >= 1.5? Or are there other things to test, like go version < 1.6?

[ghost]

go version is >= 1.5

= 1.5.2

go version < 1.6

not sure anyone has tested with 1.6 yet

[Stebalien]

I'm running IPFS with go 1.6 and haven't noticed any issues.

[whyrusleeping]

yeah, we fixed the couple issues that 1.6 brought up, so it should work. but i won't recommend it as an official supported version until we get CI running it.

For now, just saying greater than 1.5.2 should be good

[chriscool]

Ok, thanks all!