adding message which can help debug when the criterion is failing with an empty string
for now, handling skip logic on decimal/integer quesitons the same as text questions (or very simliarly)
Returning to AND condition for SL failure rather than OR
Commenting tests which break with validation

To be uncommented when we implement TP #1105 properly
reverting changes which i accidentally committed
escaping quote characters
serializing barcode criteria with "text" response type
Merge pull request #359 from kobotoolbox/tp1068

1068 -- Getting SL criteria saving in decimal + integer + barcode questions