Replace godep with vndr

Vndr has a simpler configuration and allows pointing to forked
packages. Additionally other docker projects are now using
vndr making vendoring in distribution more consistent.

Updates letsencrypt to use fork.
No longer uses sub-vendored packages.

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

vendor/golang.org/x/net/http2/Dockerfile

@@ -1,51 +0,0 @@
-#
-# This Dockerfile builds a recent curl with HTTP/2 client support, using
-# a recent nghttp2 build.
-#
-# See the Makefile for how to tag it. If Docker and that image is found, the
-# Go tests use this curl binary for integration tests.
-#
-
-FROM ubuntu:trusty
-
-RUN apt-get update && \
-    apt-get upgrade -y && \
-    apt-get install -y git-core build-essential wget
-
-RUN apt-get install -y --no-install-recommends \
-       autotools-dev libtool pkg-config zlib1g-dev \
-       libcunit1-dev libssl-dev libxml2-dev libevent-dev \
-       automake autoconf
-
-# The list of packages nghttp2 recommends for h2load:
-RUN apt-get install -y --no-install-recommends make binutils \
-        autoconf automake autotools-dev \
-        libtool pkg-config zlib1g-dev libcunit1-dev libssl-dev libxml2-dev \
-        libev-dev libevent-dev libjansson-dev libjemalloc-dev \
-        cython python3.4-dev python-setuptools
-
-# Note: setting NGHTTP2_VER before the git clone, so an old git clone isn't cached:
-ENV NGHTTP2_VER 895da9a
-RUN cd /root && git clone https://github.com/tatsuhiro-t/nghttp2.git
-
-WORKDIR /root/nghttp2
-RUN git reset --hard $NGHTTP2_VER
-RUN autoreconf -i
-RUN automake
-RUN autoconf
-RUN ./configure
-RUN make
-RUN make install
-
-WORKDIR /root
-RUN wget http://curl.haxx.se/download/curl-7.45.0.tar.gz
-RUN tar -zxvf curl-7.45.0.tar.gz
-WORKDIR /root/curl-7.45.0
-RUN ./configure --with-ssl --with-nghttp2=/usr/local
-RUN make
-RUN make install
-RUN ldconfig
-
-CMD ["-h"]
-ENTRYPOINT ["/usr/local/bin/curl"]
-