release 1.5.3

Features

• add support for configuring an outgoing proxy (requires lua-resty-http >= 0.12; see #139; thanks @grrolland
• add support for running behind reverse proxy by interpreting X-Forwarded-Host/ Forwarded-Host and X-Forwarded-Proto/Forwarded-Proto headers; see #128

Bugfixes

• correct iat checks: make sure it is not in the future rather than being too old; see #137; thanks @pamiel