Fix tests for a problem that oddly exists.
Fix tests for a problem that oddly exists.

When the conversation and messaging tests are tested alone, they pass. However, when the same set of tests are tested with all the other tests, the set fails. I traced the errors to this line, where it tried to parse 'test_user' to an int and failed. Link IDs should be a string with the format /m[0-9]+/ as defined by soc.modules.seeder.logic.providers.string.LinkIDProvider.getValue().

My fix creates a link_id properly (using soc.modules.seeder.logic.providers.string.LinkIDProvider) instead of setting an arbitrary and invalid string.

This strange issue raises two questions:
1. How does this cause an error in my tests if this code has nothing to do them?
2. Why didn't this issue cause other tests to fail before?

rhyolight/nupic.son,rhyolight/nupic.son,rhyolight/nupic.son