Update build script

- GOPATH is no longer required
- fzf repository does not have to be in GOPATH
- Build Linux binary with Go 1.5.3

src/Dockerfile.centos

@@ -13,20 +13,16 @@ RUN cd / && curl \
 
 # Install Go 1.5
 RUN cd / && curl \
-    https://storage.googleapis.com/golang/go1.5.1.linux-amd64.tar.gz | \
+    https://storage.googleapis.com/golang/go1.5.3.linux-amd64.tar.gz | \
     tar -xz && mv go go1.5
 
 ENV GOROOT_BOOTSTRAP /go1.4
 ENV GOROOT /go1.5
-ENV GOPATH /go
 ENV PATH /go1.5/bin:$PATH
 
 # For i386 build
 RUN cd $GOROOT/src && GOARCH=386 ./make.bash
 
-# Volume
-VOLUME /go
-
 # Default CMD
-CMD cd /go/src/github.com/junegunn/fzf/src && /bin/bash
+CMD cd /fzf/src && /bin/bash