Some fixes

[likemusic]

1. Fix usage STDIN constant as parameter default value in \Riverline\MultiPartParser\Converters\Globals::convert().
2. Use php://stdin or php://input depends on SAPI.
3. Create Header block in temporary stream by getallheaders() instead of $_SERVER gloabl variable.
4. Add getallheaders() polyfill.

1) Fix usage STDIN constant as parameter default value in \Riverline\MultiPartParser\Converters\Globals::convert().

STDIN constant defined only in CLI SAPI so when it used in other SAPI it produce notice like: Use of undefined constant STDIN - assumed 'STDIN' in ....

2) Use php://stdin or php://input depends on SAPI.

Use php://stdin if SAPI contains cli string. Not sure that it was rigth way, but it's better then before :)

3) Create Header of temporary stream by getallheaders() instead of $_SERVER gloabl variable.

Iterating over $_SERVER global variable instantinate multiple Content-Type headers, because in some configurations $_SERVER contains both HTTP_CONTENT_TYPE and CONTENT_TYPE keys. Therefore header with key content-type becomes an array. So in \Riverline\MultiPartParser\StreamedPart::parseHeaderContent() an Error will thown on $parts = explode(';', $content);.

4) Add getallheaders() polyfill.

In some configurations getallheaders() could be not defined.