Typescript types incorrect: Missing 'main' property from Action.Exec

[jthomas]

openwhisk-client-js/lib/main.d.ts

Lines 248 to 252 in 7fd311f

	interface Exec {
	kind: Kind;
	code: string;
	binary?: boolean
	}

Should have an optional main attribute used to set the function handler for the action code. As seen in action here: https://github.com/apache/openwhisk-runtime-nodejs/blob/master/core/nodejsActionBase/runner.js#L32

Will submit a PR.