pbr should be first in the requirements list

Order is important for the pip depend resolver.

Change-Id: I876485a20b126e13102c0d47aec578f64a9de555
[API]: Don't allow invalid port numbers

Change-Id: I40041f764272c7e30e92b27b75a9890212104739
[ALL] Add Gearman KEEPALIVE options

This requires the lastest development version of python-gearman
to support the new keepalive options. Using these options (off
by default) will solve the problem when the Gearman job server
gets paused/unpaused in a cloud environment, but the clients and
workers never recognize that they are indeed disconnected.

WARNING: Not backwards compatible with older versions of the
python-gearman driver, even if the SSL and keepalive options
are not specified. This is a change in behavior.

Change-Id: Ic8db6676f7408364b6fe9a8690deb72bb6e2772c
Remove deprecated DEVICES.LOADBALANCERS column

Change-Id: Ifa98b165d8137f735300e06ddf1356adc26f08a5