Add initial session support

This works, but still needs tests.
Add session usage example
Initial support for parsing common/alt names

This appears to follow both the specification and browser behaviour, but this
should be double-checked before merge.
Use stream_context_get_options() for 5.2 support
Use a more descriptive SSL failure error
Test expired and revoked SSL certificates
Document certificate verification method params
Add SNI, SAN and invalid domain tests
Mark SSL tests as skipped if we don't have support
First pass at cookie support

Still needs tests.
Trim all cookie keys and values
Add initial proxy support
Use a class for proxy support
Update example for authentication
Add documentation on using proxies
Readme fix related to PSR-0 class loader
Merge pull request #71 from fulopattila122/master

Readme fix related to PSR-0 class loader
Merge pull request #70 from rmccue/proxy

Add full proxy support, major props @ozh
Ensure casting a cookie to a string uses the value
Implement the array-like interfaces for Cookie_Jar