[#76] Wrote test confirming issue

- Confirms the issue, and indicates that the problem happens in the
  model, during update (and is not a representation/view problem)
[#76] merge new with old config before writing

- Wrote routine "getConfigForSubkey", which will return the
  configuration for a given subkey. This can then be used in patchKey()
  operations when merged with the changes.
Merge branch 'hotfix/76'

Close #76