fixing #33
add content-available support. fix #36
change version number to a2
let the service be able to report some information
APNS: detect EOF early.
fix #38
no deadline for read. read forever
APNS: retry on error.
APNS: retry & set deadline
update linkes in readme.
fix #39.
new version.
will not use uuid.

Reason: github.com/nu7hatch/gouuid is not well supported by
goimports.
readme.
merge uniqush master