Fix image optimisers in Docker

[leebenson]

Currently, only png and gif image optimises correctly build binaries in Docker (and possibly locally, too):

pngquant-bin@3.1.1 postinstall /src/node_modules/pngquant-bin
node lib/install.js

⚠ The /src/node_modules/pngquant-bin/vendor/pngquant binary doesn't seem to work correctly
⚠ pngquant pre-build test failed
ℹ compiling from source
✖ Error: pngquant failed to build, make sure that libpng-dev is installed
at ChildProcess.exithandler (child_process.js:252:12)
at emitTwo (events.js:125:13)
at ChildProcess.emit (events.js:213:7)
at maybeClose (internal/child_process.js:887:16)
at Process.ChildProcess._handle.onexit (internal/child_process.js:208:5)

optipng-bin@3.1.4 postinstall /src/node_modules/optipng-bin
node lib/install.js

✔ optipng pre-build test passed successfully

mozjpeg@4.1.1 postinstall /src/node_modules/mozjpeg
node lib/install.js

⚠ The /src/node_modules/mozjpeg/vendor/cjpeg binary doesn't seem to work correctly
⚠ mozjpeg pre-build test failed
ℹ compiling from source
✖ Error: autoreconf -fiv && ./configure --disable-shared --prefix="/src/node_modules/mozjpeg/vendor" --bindir="/src/node_modules/mozjpeg/vendor" --libdir="/src/node_modules/mozjpeg/vendor" && make --jobs=4 && make install --jobs=4
Command failed: autoreconf -fiv
/bin/sh: 1: autoreconf: not found

at ChildProcess.exithandler (child_process.js:252:12)
at emitTwo (events.js:125:13)
at ChildProcess.emit (events.js:213:7)
at maybeClose (internal/child_process.js:887:16)
at Socket.stream.socket.on (internal/child_process.js:340:11)
at emitOne (events.js:115:13)
at Socket.emit (events.js:210:7)
at Pipe._handle.close [as _onclose] (net.js:546:12)

gifsicle@3.0.4 postinstall /src/node_modules/gifsicle
node lib/install.js

✔ gifsicle pre-build test passed successfully
npm notice created a lockfile as package-lock.json. You should commit this file.