support and describe building static binaries

Dockerfile.build

@@ -0,0 +1,15 @@
+FROM ubuntu
+RUN apt-get update -yy && \
+	apt-get install -yy git make curl libxml2-dev libxmlsec1-dev pkg-config
+
+RUN curl -s https://storage.googleapis.com/golang/go1.7.linux-amd64.tar.gz | tar -C /usr/local -xzf -
+ENV GOPATH=/go
+ENV PATH=$PATH:/usr/local/go/bin:/go/bin
+RUN mkdir -p /go/bin
+
+ADD . /go/src/github.com/crewjam/go-xmlsec
+WORKDIR /go/src/github.com/crewjam/go-xmlsec
+RUN go get github.com/crewjam/errset
+RUN go build -o /bin/xmldsig ./examples/xmldsig.go
+RUN ldd /bin/xmldsig || true
+RUN /bin/xmldsig --help || true