Fix APNS_FEEDBACK_HOST url

Fixes #85
Fixed the issue with production and sandbox addresses for APNS Feedback Service beind mixed up
apns: Make APNS_MAX_NOTIFICATION_SIZE a setting

Also bump the limit from 256 to 2048 due to the increase at iOS8's release.

Fixes #79
fix `HexIntegerField.get_prep_value` when value is already a string

value may already be an integer so trying to create a base 16 int from
it fails
Change SSLv3 to TLSv1
apns: Fix bad reference to max notification size

Fixes #93
Thanks, Jay Camp
README: Fix an unexpected indentation error
README: Remove some badly-parsed indents
fix APNS test after introduction of APNS_MAX_NOTIFICATION_SIZE
added support for GCM time_to_live parameter
Release v1.2.0
cleanup unnecessary return and redundant error checking
handle timeout in apns feedback socket with python 3
decoupled _gcm_send error handling; adjusted tests accordingly
expose time_to_live in gcm_send_bulk_message
fix return value when gcm bulk is split in batches
Merge remote-tracking branch 'upstream/master'. Sync with original repo.
Added more REST Framework details to the readme. Example URLs.