Add read_reply method to Pusher
Add reply object and tests
Remove mistaken comment
Add description of reply status codes
Merge https://github.com/grocer/grocer
Add note about what this fork does
Fail notifications if the payload byte size is > 256
Use consistent Grocer::Error for all Errors

So clients have a single, and sane, constant to rescue. The only
outstanding case is the CertificateExpiredError, which is a module we
use to tag the underlying SSLError.

Perhaps @alindeman has an idea for handling that case?
- rename Grocer::InvalidPayloadError to Grocer::PayloadTooLargeError
- pull to checking for too large a payload into its own constants and methods.  payload_too_large? is public so clients can perform their own validation instead of using exception handling
- similar cleanup in the tests and new tests for payload_too_large?
remove trailing whitespace
remove shared examples from payload size tests
Merge branch 'validate-payload-size' of https://github.com/johnnaegle/grocer into validate-payload-size

Conflicts:
	lib/grocer.rb
	lib/grocer/notification.rb