Supporting nested functions when serving functions locally

[tinaliang]

Description

Allow for nested functions to be locally emulated in response to customer issue #481 . Nested functions can now be accessed using dot notation. For example, given
exports.funcName = {
func1: functions.database.ref().onCreate(...),
func2: functions.https.onRequest(...)
}
func1 and func2 can be accessed using funcName.func1 and funcName.func2 respectively.

Depends on googlearchive/cloud-functions-emulator#191

Scenarios Tested

Tested against https nested functions two levels deep and database nested functions one level deep.

Sample Commands

[coveralls]

Coverage remained the same at 57.502% when pulling ec13756 on tl-nestedfunctions into 0a101ca on master.

[coveralls]

Coverage remained the same at 57.502% when pulling ec13756 on tl-nestedfunctions into 0a101ca on master.

[coveralls]

Coverage remained the same at 57.502% when pulling 80243cc on tl-nestedfunctions into 0a101ca on master.

[laurenzlong]

You should keep supplying the "firebase" option when deploying the functions, since it's still useful. Looks good otherwise.

[laurenzlong]

Can you also update package.json to beta.4 of GCF emulator? And only merge this branch once that's actually released.

[laurenzlong]

Approved, please merge once GCF emulator beta.4 is released.