Improve yard doc for NodeSet::Base somewhat

Signed-off-by: Ken Barber <ken@bob.sh>
Merge branch 'fix_yard_for_nodeset_base'

* fix_yard_for_nodeset_base:
  Improve yard doc for NodeSet::Base somewhat
- Change the tmp path for the vagrant_projects directory to be under projects root directory at '.rspec_system'
- Add environment variable, RSPEC_SYSTEM_TMP,  to override the TMP path.
- Issue #14
Merge pull request #20 from treydock/system_tmp_changes

Change the tmp path for the vagrant_projects directory
Release 1.7.0

Signed-off-by: Ken Barber <ken@bob.sh>