Adding support for PHP 5.3 and up. Greatly improves potential user base and PHP 5.4 wasn't being taken advantage of.

Signed-off-by: Ben Corlett <bencorlett@me.com>
Merge branch 'compatibility'

Signed-off-by: Ben Corlett <bencorlett@me.com>

Conflicts:
	src/OAuth/ServiceFactory.php
	tests/OAuth/Unit/Common/Http/UriTest.php
	tests/OAuth/Unit/Common/Storage/MemoryTest.php
	tests/OAuth/Unit/Common/Storage/RedisTest.php