Install dependencies before crosscompiling (fixes #27)

Author: surma

crosscompile.sh

@@ -1,5 +1,6 @@
 #!/bin/bash
 
+go get -d ./...
 for target in darwin:amd64 linux:amd64 linux:386 linux:arm windows:amd64; do
   echo "Compiling $target"
   export GOOS=$(echo $target | cut -d: -f1) GOARCH=$(echo $target | cut -d: -f2)