Merge pull request #27 from daniellemayne/2014.08

2014.08 bugz 5126: added os mapping to descriptive names
Merge pull request #29 from daniellemayne/2014.08

2014.08: added null checks and bugfix 5175
Merge pull request #31 from daniellemayne/2014.08

reuse service instance where possible
volume support
storage pool fix for datacenter level pools
alterVM to allow addition of new hard disk + regionId fix