Allow setting of maxBuffer for packing external modules

[mhodgson]

I received the following error when trying to compile in Docker: stderr maxBuffer exceeded. It stems from the npm-programatic module and its use of exec when we install external dependencies. I have a PR opened there to add a setting for maxBuffer: Manak/npm-programmatic#8

I don't recommend merging this until that PR is accepted, but I wanted to make this PR in the meantime for anyone else that runs into this problem.

This PR adds a setting called packExternalModulesMaxBuffer that is passed to the npm exec for installing external dependencies.

[mhodgson]

OK, the PR on npm-programmatic was accepted so this now uses a non-forked version. Ready to merge.

[yashafromrussia]

Running into a similar issue. I'm currently using @mhodgson's fork that works perfectly. Hey @thenikso, any plans on merging this soon?

[jelder]

@thenikso The other PR (Manak/npm-programmatic#8) has been merged. Think we could get this one merged soon, too?

[hassankhan]

We shouldn't hardcode a Webpack dependency since #83 means a user has to install Webpack as a peer dependency.

[HyperBrain]

@mhodgson Can you update (rebase this PR) onto the current master? I think the issue still is present on Docker as nothing changed and the npm-programmatic version in master is still 0.0.5?

@gorjuspixels Can you confirm that the issue still exists with serverless-webpack 2.2.0?

[mhodgson]

@HyperBrain all set.

[HyperBrain]

@mhodgson Great 👍 ! I will check it out tomorrow and do some tests (with master and the 3.0.0 branch).
If everything works well, I'll merge it into master.

[HyperBrain]

Tests against master, v3.0.0 and v3.0.0-individual-packaging were successful. I also noticed a speed-up while packaging.

The PR is ready to be merged -> nevertheless I will wait. Depending on the status (quality/testing) of the individual packaging branch the merge target might be the v3.0.0 branch. If everything goes well, that will be released next week.

[HyperBrain]

@mhodgson If you check the "enable edits by maintainers" checkbox in the PR, I can add some README changes to the PR and retarget it before I'll merge it next week.

[mhodgson]

@HyperBrain checked.

[HyperBrain]

@mhodgson All v3 features are now merged into the v3.0.0 branch. Unfortunately the merge left this PR with conflicts. IMO the easiest way would be to create a new PR with these changes (it's just 2 lines of code) from the latest upstream v3.0.0 branch. Can you do that, so that I can get it into v3?

[mhodgson]

@HyperBrain done: #185