Requirement update: OpenDaylight Be as default

Requirement update: OpenDaylight Be as default

Installers should support the installation of OpenDaylight
Beryllium release as default.
OpenDaylight Beryllium became available in the form of
stable release candidates during the final stages of
the OPNFV Brahmaputra release composition.
In was found that OpenDaylight Beryllium provides
for several improvements over the Lithium release.
This includes improved stability of tests as well as
support for several projects (e.g. SFC, SDNVPN, etc.)
All installers have successfully reported integration
with OpenDaylight Beryllium.
As a consequence, the original requirement for
support of OpenDaylight Lithium was changed to support
OpenDaylight Beryllium as default.

JIRA: GENESIS-6

Change-Id: I4c09b2c4b30c7c45904fbc9b599cbaf2d43f3aa7
Signed-off-by: Frank Brockners <fbrockne@cisco.com>