added ability to create phar file with box

added the ability compile security-checker into a phar archive with [box][1]. 

for that it was necessary to add a little bit of code to extract the certificate to the tmp directory, because curl is not able to read from a phar stream wrapper.
code part taken from [guzzle http client][2] but changed the hash algorithm from md5 to sha1


[1]: http://box-project.org/
[2]: https://github.com/guzzle/guzzle/blob/v3.7.2/src/Guzzle/Http/Client.php#L336