Update developer docs to update to Go1.4

DEVELOPERS.md

@@ -20,9 +20,9 @@ $ sudo apt-get install yasm
 Download Go 1.3+ from [https://golang.org/dl/](https://golang.org/dl/) and extract it into ``${HOME}/local`` and setup ``${HOME}/mygo`` as your project workspace folder.
 For example:
 ```sh
-$ wget https://storage.googleapis.com/golang/go1.3.3.linux-amd64.tar.gz
+$ wget https://storage.googleapis.com/golang/go1.4.linux-amd64.tar.gz
 $ mkdir -p ${HOME}/local
-$ tar -C ${HOME}/local -xzf go1.3.3.linux-amd64.tar.gz
+$ tar -C ${HOME}/local -xzf go1.4.linux-amd64.tar.gz
 $ export PATH=$PATH:${HOME}/local/go/bin
 $ mkdir -p $HOME/mygo
 $ export GOPATH=$HOME/mygo