[ticket/11603] Fix github api url and use curl with valid user agent

PHPBB3-11603
[ticket/11603] Rename network to forks and fix handling

PHPBB3-11603
[ticket/11603] Fix github API calls

- Some URLs changed
- Response is a plain array now
- Added error messages when API limit is reached

PHPBB3-11603
[ticket/11603] Fix spacing and add some comments

PHPBB3-11603
[ticket/11603] Split api_request into two functions (query only vs. full url)

PHPBB3-11603
[ticket/11603] Avoid using cURL

PHPBB3-11603
[ticket/11603] Throw RuntimeExceptions instead of using exit()

PHPBB3-11603
Merge remote-tracking branch 'nickvergessen/ticket/11603' into develop-olympus

* nickvergessen/ticket/11603:
  [ticket/11603] Throw RuntimeExceptions instead of using exit()
  [ticket/11603] Avoid using cURL
  [ticket/11603] Split api_request into two functions (query only vs. full url)
  [ticket/11603] Fix spacing and add some comments
  [ticket/11603] Fix github API calls
  [ticket/11603] Rename network to forks and fix handling
  [ticket/11603] Fix github api url and use curl with valid user agent