Recommender only ever trained once

[reckart]

Describe the bug Recommender only ever trained once. All subsequent times it reports "Training already in progress"

To Reproduce Steps to reproduce the behavior:

1. Try setting up a trainable recommender e.g. using the LogOnlyRecommender
2. Connect INCEpTION to it
3. Annotate stuff and observe the log output - notice the first time a training is logger, but the second and later times it claims to still be training.

Expected behavior When the training is done or aborts, the lock should be released such that training can be done again.

Please complete the following information:

• Version: 0.1.0-dev