added the option to use curl through exec()

this enables an async mode; the exec command will run in the background as the script continues execution
fix funky version
Merge branch 'master' of https://github.com/stripes39/raven-php into stripes39-master

Conflicts:
	lib/Raven/Client.php
Clean up abstraction for curl method
Add async curl handler via curl_multi
Bump protocol to 5
0.9.0
Fix Raven_Tests_ClientTest::testGetAuthHeader
Merge pull request #155 from siwinski/pr-fix-testGetAuthHeader

Fix Raven_Tests_ClientTest::testGetAuthHeader
Merge branch 'master' into customfix

Conflicts:
	lib/Raven/Client.php