Simplified to use a single /hxmetadata volume, as this is the
most common configuration. Small sites don't need multiple
volumes, and big sites have an array of hardware options, only
some of which require a two-volume solution for metadata to
maintain performance.
Changed default replica ServerID from p4d_fr_bos to p4d_ha_bos,
to promote modern 2018.2 high availability replicas that can
be created with the mkrep.sh in SDP 2019.1+. The replica is not
actually created with the Helix Installer, just referenced
as a sample ServerID name.
Extended '-B' flag to cleanup temp dir used by install_sdp_python.sh.
Changed behavior to bail on failure to cleanup temp dirs, as this
could result in wasted time building outdated versions of
P4Python, etc.
Added '-i <helix_installer_branch>' debugging flag to support
testing of Helix Installer from the dev branch. Moved this and
the '-D' flag to a new doc section titled DEBUGGING OPTIONS.