Fix Codegen fail for MacPorts users

[manicmaniac]

Problem

I installed node and npm from MacPorts and don't use Homebrew.
When I build my project, it says node is not found.

... /Pods/Apollo/scripts/check-and-run-apollo-cli.sh: line 45: node: command not found
error: Apollo CLI requires Node 8 or higher to be installed.

But actually node and npm are installed under /opt/local/bin, that is default MacPorts' executable path.

Cause

Xcode doesn't consider MacPorts default path /opt/local/bin and doesn't respect .bashrc.

Solution

Added default MacPorts bin path to codegen script.

[apollo-cla]

@manicmaniac: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Meteor Contributor Agreement here: https://contribute.meteor.com/

[designatednerd]

Awesome! I'll merge this once CI does its thing

[designatednerd]

OK Travis passed, looks like the webhook just didn't call back. Merging!