Does not compile for 32 bit architecture

[nicksantamaria]

I encountered an issue when compiling a project with this library with the GOARCH=386.

vendor/github.com/brotherpowers/ipsubnet/ip.go:16:27: constant 4294967295 overflows int

This is the line in question:

ipsubnet/ip.go

Line 16 in 30bc98f

subnet_mask: 0xFFFFFFFF << uint(32-networkSize),

[rmasci]

I have a version that does compile for 32 bit -- I'd do a pull request but the calls change from int to int64, so people who are on 64 bit systems would have to change from int to int64 in their code.

https://github.com/rmasci/ipsubnet