let subflow add node-red context to status so i18n works

[dceejay]

For all those nodes thaht don't specify it.
So that subflow status then works ok

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Proposed changes

the subflow seems to need the correct node-red: context for i18n of status message to work correctly - other wise they just show the untranslated version (eg common.status.OK)
This fix checks to see if the text starts with common and if so prepends the node-red: context.
About 80% of core nodes do NOT have the context set - so we either need to do something like this or fix all the nodes - (and then the 3rd party ones)

Checklist

• I have read the contribution guidelines
• For non-bugfix PRs, I have discussed this change on the mailing list/slack team.
• I have run grunt to verify the unit tests pass
• I have added suitable unit tests to cover the new/changed functionality

[coveralls]

Coverage decreased (-0.005%) to 77.604% when pulling 2f4dcba on subflow-status-i18n into 2aef99c on master.