feature #1678: monitor system ds probe for kvm and xen

I'm not happy passing parameters as argument possition as these
are also used for collectd. As soon as we add a new parameter
the probe should be changed to get another ARG possition.

A better way could be adding parameters in the form:

  DATASTORE_LOCATION=/my/datastores OTHER_VAR=other_value

Parsing this and set the environment with those values.

No time, no shine...
feature #1678: bug in install.sh
Merge branch 'feature-1678' of git.opennebula.org:one into feature-1678
Feature #1678: DS inserts clone & ln target attributes into each disk
Feature #1678: Method to calculate VM storage usage in scheduler
Feature #1678: Filters VMs that do not fit in the image DS
Feature #1678: Make all disk related variables long long
Feature #1678: Host monitorization copies DS info to each system DS. Assumes all DS are shared.
Feature #1678: CLI does not hide system DS capacity