Bump kombu version and add amqp version

oslo.messaging now implements rabbitmq heartbeat.

py-amqp (the underlying low library to connect to rabbitmq) has a
working support of heartbeat since 1.4.0. So we need at least
that version.

Given that Trusty has 3.0.7 of kombu and the authors have indicated
that amqp>=1.3.3,<2.0 would work with that version, we can use
amqp 1.4.0 with kombu 3.0.7.

So this change raises the kombu requirement to '>=3.0.7' and
amqp to '>=1.4.0'

Change-Id: I2b111af06e27caf1436cbda2de5be547c7d8790c
Closes-bug: #1436769

global-requirements.txt

@@ -1,5 +1,6 @@
 aioeventlet>=0.4
 alembic>=0.7.2
+amqp>=1.4.0
 anyjson>=0.3.3
 argparse
 argcomplete>=0.6.8  # Apache-2.0
@@ -47,7 +48,7 @@ kazoo>=1.3.1
 keystonemiddleware>=1.5.0
 pyScss>=1.2.1,<1.3  # MIT License
 django-pyscss>=1.0.3,<2.0.0  # BSD License (2 clause)
-kombu>=2.5.0
+kombu>=3.0.7
 libvirt-python>=1.2.5                   # LGPLv2+
 lockfile>=0.8
 lxml>=2.3