Added dependencies to install ceilometer

In a case where ceilometer is installing on a control node that
might not have other services like glance on it, ceilometer
requires:  libffi-dev libssl-dev in order to build/install
Nodes installing boot-stack for example would already have
the above dependencies included.

Change-Id: I2f5b7643005b81e3ed85a01ff60ce60f155b35b6
Merge "Added dependencies to install ceilometer"