Simplified Google Drive API access

Simplified Google Drive API access based on google/apiclient

How to run the examples

set up the Google client secret and download it as JSON file (see below id you need instructions for that)
move it to the examples/config folder
CLI version
- rename it to app_secret_cli.json
- open terminal, go to the examples/cli folder
  - run php index.php
  - open the URL
  - enter the verification code
  - now you should see a (partial) list of the content of your drive
  - run it again, now you should see the same list without the hassle of managing the verification code
HTTP version
- rename it to app_secret_http.json
- set up a web server with examples/http as doc root
- open http://< your (local) web server url >
  - given you have a local system gd-test.app set up:
    - http://gd-test.app/index.php

go to https://console.developers.google.com
create new or open existing project
got to API Manager, enable Google Drive API
go to Credentials and create new OAuth Client ID
if it is the first time, you need to setup the consent screen
- enter product name and an optional URL
CLI version
- In the list with application types, choose other and give it a name
HTTP version
- In the list with application types, choose Web Application and give it a name
- In the field Authorized redirect URIs enter:
  - http://< your (local) web server url >/< OAuth2 callback handler >
    - to run the examples (given you have a local system gd-test.app set up):
    - http://gd-test.app/redirecttarget.php
Confirm the popup with client id and secret -> you don't need to remember those now
Instead, download the whole credentials as json from the list with all client IDs
move the file to any destination you like an make sure you give the correct path to the service