Helper function to "promisify" method calls

[jykae]

Consider adding helper function to core helper functions, use of Promises would make chained Meteor calls easier to read.

Reference: https://forums.meteor.com/t/start-using-async-await-instead-of-promises-and-callbacks/17037/52

[jykae]

Blog post also released: https://blog.meteor.com/using-promises-on-the-client-in-meteor-fb4f1c155f84#.dlpuuizcu

[mauriciovieira]

This could be useful especially in callback chained functions we have inside our core.

[marla-singer]

Close this issue because the helper function is done

platform/apinf_packages/core/helper_functions/promisify_call.js

Lines 9 to 17 in 71770c6

	// Validates Promisify Meteor.call, for better response handling.
	export default function promisifyCall (...args) {
	return new Promise((resolve, reject) => {
	// Call function with arguments and callback function
	Meteor.call(...args, (err, response) => {
	return err ? reject(err) : resolve(response);
	});
	});
	}