Support rotate images with rotate option

[drqwerty]

Hi.

I needed to rotate images so I added an option for it.

It works quite well, although I have not been able to run the tests due to problems with some packages :(.

TLDR: from me to you :)

[lukechilds]

@drqwerty thanks for this, it's a nice addition!

Could you add a usage example and a test like positioning for example: https://github.com/lukechilds/merge-images#positioning

Yeah I'm aware tests are broken atm, I'll fix that as soon as I'm able but not quite sure when that'll be.

Feel free to take it on on your own in the meantime if you want to!

[lukechilds]

You don't seem to be using this value anywhere. I think it can be removed.

[RuiSiang]

I think I found the problem
There has been a change in node-canvas' dependencies
"libjpeg8-dev" should be changed to "libjpeg-dev" or "libjpeg62-turbo-dev"

language: node_js
node_js: node
addons:
  apt:
    sources:
      - ubuntu-toolchain-r-test
    packages:
      - libcairo2-dev
      - libjpeg8-dev
      - libpango1.0-dev
      - libgif-dev
      - g++-4.9
env:
  - CXX=g++-4.9
script: npm run lint && npm test
after_success: npm run coverage
notifications:
  email:
    on_success: never