Cannot build snowflake/proxy

Hello! I want to install the snowflake proxy on my raspberry pi, but I can't seem to build it. I updated my system via apt-get update/update succesfully and the installation of git and golang were also successful. But after cloning the git, I went to /home/pi/snowflake/proxy and when I enter go build the system gives me this:

pi@raspberrypi:~/snowflake/proxy $ go build
main.go:5:2: cannot find package "git.torproject.org/pluggable-transports/snowflake.git/v2/common/event" in any of:
        /usr/lib/go-1.7/src/git.torproject.org/pluggable-transports/snowflake.git/v2/common/event (from $GOROOT)
        ($GOPATH not set)
main.go:12:2: cannot find package "git.torproject.org/pluggable-transports/snowflake.git/v2/common/safelog" in any of:
        /usr/lib/go-1.7/src/git.torproject.org/pluggable-transports/snowflake.git/v2/common/safelog (from $GOROOT)
        ($GOPATH not set)
main.go:13:2: cannot find package "git.torproject.org/pluggable-transports/snowflake.git/v2/proxy/lib" in any of:
        /usr/lib/go-1.7/src/git.torproject.org/pluggable-transports/snowflake.git/v2/proxy/lib (from $GOROOT)
        ($GOPATH not set)

What is the problem here, and how can I fix it? Whe I look into /usr/lib/go-1.7/src/ there is no git.torproject.org subdirectory I hope, you can help me.