Feat: Use old version of chromium

[benperiton]

This makes it easy to install this package and use an older version of chromium so that things like #17 work, but it's not very nice having to set the PUPPETEER_CHROMIUM_REVISION=526987 on install as well as in the package.json - not really sure if there is a better way.

To be honest, this might not be needed if someone can figure out why transform:rotate doesn't work, but I'll leave it here in case it helps.

Related to #22

[Zulko]

Hey, I like this PR but is the export PUPPETEER_CHROMIUM_REVISION=526987 mandatory ?
I am trying to make the installation/setup as simple as possible, so that even people with no clue what NPM is can use it.

I'd rather keep the installation instructions clear, and in the future always keep examples and code aligned on the most recent pupetteer and chromium (as I expect improvements).

Then there would be a special section in the docs explaining that for people wanting reliability they can use export PUPPETEER_CHROMIUM_REVISION=526987 (in docker, travis, etc.).

Would that make sense ?

[benperiton]

Yea I'm not overly keen on the export PUPPETEER_CHROMIUM_REVISION=526987 either.
I'll have a look and see if there's a better way to use the default value from puppeteer unless that ENV is set.

[DanielRuf]

cross-env, shelljs / shx could be somehow helpful to give some ideas for possible solution.