Write watchdog file that performs exclusions and adapts stimuli database

[felixbinder]

watchdog performing exclusions and adapting stimuli (sometimes we automatically want to keep track of exclusion to collect an equal number of post-exclusion observations per stimuli if only a subset are shown etc.). See balance_stims.py in curiophysion

The watchdog should operate on the level of records in the stimuli database, where we have both a counter for how often an experiment has been served. The watchdog should add a counter for verified_games so that we can make sure we get enough observations after exclusion for each record in stimuli.

• make it work on records in stimuli database
• make it write into records in stimuli database

save into numVerifiedGames and verifiedGames