Address intermittent problem with markers not appearing in the Emotiv data stream

[teonbrooks]

We often have a problem where the markers from the screen presentation is not integrated in the data file. This might be a dupe, but adding to track development and progress.

[jdpigeon]

Error has been isolated to the emotiv utils functions. Markers are appearing correctly when using Muse which means that stimulus presentation and data recording are operating correctly.

It seems that with the newer versions of Cortex, several API functions have become flaky. Notably injectMarker and unsubscribe don't seem to behaving as described in documentation.