Change _-prefixed/"internal" methods into private
Create a public setter for controls_scanning
Update private setter/getter names in GlobalSettings
Merge pull request #87 from erran/controls-scanning-setting

Update Global Settings
Use attr_accessor instead of a custom setter

GlobalSettings#control_scanning= did not set @control_scanning which
caused the call to #add_control_scanning_to_xml from #save method to
revert to the original state.
Merge pull request #89 from erran/fix-global-settings-save

Use attr_accessor instead of a custom setter in GlobalSettings
Use the #id reader instead of the nil @id variable
Merge pull request #90 from erran/fix-no-method-error-in-scan_template-delete

Use the #id reader instead of the nil @id variable
Bumping version for release.