Add scripts to run sytest on jenkins (#207)

jenkins/prepare-dendrite.sh

+#!/bin/bash
+#
+# build the dendrite binaries into ./bin
+
+cd `dirname $0`/..
+
+set -eux
+
+export GOPATH=`pwd`/.gopath
+export PATH="${GOPATH}/bin:$PATH"
+
+go get github.com/constabulary/gb/...
+gb build

jenkins/test-monolith.sh

+#!/bin/bash
+
+set -eux
+
+cd `dirname $0`/..
+
+: ${WORKSPACE:="$(pwd)"}
+export WORKSPACE
+
+# remove any detritus from last time
+rm -f sytest/server-*/*.log sytest/results.tap
+
+./jenkins/prepare-dendrite.sh
+
+if [ ! -d "sytest" ]; then
+    git clone https://github.com/matrix-org/sytest.git --depth 1 --branch dendrite
+else
+    git -C sytest fetch --depth 1 origin dendrite
+    git -C sytest reset --hard FETCH_HEAD
+fi
+
+./sytest/jenkins/prep_sytest_for_postgres.sh
+
+./sytest/jenkins/install_and_run.sh \
+    -I Dendrite::Monolith \
+    --dendrite-binary-directory "$WORKSPACE/bin" || true