BIS-1371: Fixed exporting issue when there are several colored elements by replacing greedy regex with a lazy one.

BIS-1049: Fixing the exception, which occurs when exporting non text Json nodes (in the spreadsheet).

BIS-1366: Refactored error handling for pattern assignment. Added AbstractCommonEntityTest for testing functionalities common for Experiments, Samples and DataSets

BIS-1335: In exported ZIP, removed empty experiment folders, which contained no name (when provided).