arm: add install script, fix Makefile (#2824)

* be like the SDK makefile

* arm: add install script, fix Makefile

* ...

scripts/install/install_tendermint_arm.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+
+# XXX: this script is intended to be run from
+# a fresh Digital Ocean droplet with Ubuntu
+
+# upon its completion, you must either reset
+# your terminal or run `source ~/.profile`
+
+# as written, this script will install
+# tendermint core from master branch
+REPO=github.com/tendermint/tendermint
+
+# change this to a specific release or branch
+BRANCH=master
+
+sudo apt-get update -y
+
+# get and unpack golang
+curl -O https://storage.googleapis.com/golang/go1.11.2.linux-armv6l.tar.gz
+tar -xvf go1.11.2.linux-armv6l.tar.gz
+
+# move go folder and add go binary to path
+sudo mv go /usr/local
+echo "export PATH=\$PATH:/usr/local/go/bin" >> ~/.profile
+
+# create the goApps directory, set GOPATH, and put it on PATH
+mkdir goApps
+echo "export GOPATH=$HOME/goApps" >> ~/.profile
+echo "export PATH=\$PATH:\$GOPATH/bin" >> ~/.profile
+source ~/.profile
+
+# get the code and move into repo
+go get $REPO
+cd "$GOPATH/src/$REPO"
+
+# build & install
+git checkout $BRANCH
+# XXX: uncomment if branch isn't master
+# git fetch origin $BRANCH
+make get_tools
+make get_vendor_deps
+make install
+
+# the binary is located in $GOPATH/bin
+# run `source ~/.profile` or reset your terminal
+# to persist the changes