restructure: move bin/ and tests/ to src/

Also add symlinks from the old `bin/` and `tests/` locations to avoid
breaking scripts and other tools.

Motivations:

  * Scripts and tests no longer have to do dubious things like:

        require('ep_etherpad-lite/node_modules/foo')

    to access packages installed as dependencies in
    `src/package.json`.

  * Plugins can access the backend test helper library in a non-hacky
    way:

        require('ep_etherpad-lite/tests/backend/common')

  * We can delete the top-level `package.json` without breaking our
    ability to lint the files in `bin/` and `tests/`.

    Deleting the top-level `package.json` has downsides: It will cause
    `npm` to print warnings whenever plugins are installed, npm will
    no longer be able to enforce a plugin's peer dependency on
    ep_etherpad-lite, and npm will keep deleting the
    `node_modules/ep_etherpad-lite` symlink that points to `../src`.

    But there are significant upsides to deleting the top-level
    `package.json`: It will drastically speed up plugin installation
    because `npm` doesn't have to recursively walk the dependencies in
    `src/package.json`. Also, deleting the top-level `package.json`
    avoids npm's horrible dependency hoisting behavior (where it moves
    stuff from `src/node_modules/` to the top-level `node_modules/`
    directory). Dependency hoisting causes numerous mysterious
    problems such as silent failures in `npm outdated` and `npm
    update`. Dependency hoisting also breaks plugins that do:

        require('ep_etherpad-lite/node_modules/foo')

src/tests/frontend/travis/runnerLoadTest.sh

@@ -0,0 +1,51 @@
+#!/bin/sh
+
+pecho() { printf %s\\n "$*"; }
+log() { pecho "$@"; }
+error() { log "ERROR: $@" >&2; }
+fatal() { error "$@"; exit 1; }
+try() { "$@" || fatal "'$@' failed"; }
+
+MY_DIR=$(try cd "${0%/*}" && try pwd) || exit 1
+
+# reliably move to the etherpad base folder before running it
+try cd "${MY_DIR}/../../../"
+
+try sed -e '
+s!"loadTest":[^,]*!"loadTest": true!
+# Reduce rate limit aggressiveness
+s!"points":[^,]*!"points": 1000!
+' settings.json.template >settings.json
+
+log "Assuming bin/installDeps.sh has already been run"
+node node_modules/ep_etherpad-lite/node/server.js "${@}" >/dev/null &
+ep_pid=$!
+
+log "Waiting for Etherpad to accept connections (http://localhost:9001)..."
+connected=false
+can_connect() {
+    curl -sSfo /dev/null http://localhost:9001/ || return 1
+    connected=true
+}
+now() { date +%s; }
+start=$(now)
+while [ $(($(now) - $start)) -le 15 ] && ! can_connect; do
+    sleep 1
+done
+[ "$connected" = true ] \
+    || fatal "Timed out waiting for Etherpad to accept connections"
+log "Successfully connected to Etherpad on http://localhost:9001"
+
+# Build the minified files
+try curl http://localhost:9001/p/minifyme -f -s >/dev/null
+
+# just in case, let's wait for another 10 seconds before going on
+sleep 10
+
+log "Running the load tests..."
+etherpad-loadtest -d 25
+exit_code=$?
+
+kill "$ep_pid" && wait "$ep_pid"
+log "Done."
+exit "$exit_code"