Updated code to use v3.3.0 of the concrete-thrift schema
Updated getTokensForEntityMentionID() to work with current Thrift schema

The function Communication.prototype.getTokensForEntityMentionID
was accessing a tokenization using the data structure:

  tokenization.tokenList

when the correct data structure (for the current version of
concrete-thrift) is:

  tokenization.tokenList.tokens