Issues in running this code in 2021/02

[gabrer]

Some of the issues you might face in running this repository and related fixes [UPDATED to 2021/02]:

• The 'elmo' model to be used is the _small_ model with output size 128 (otherwise, it will rise a dimensionality issue);
• A folder 'models' needs to be manually created in the root of the repository;
• Using Java11, it requires the CoreNLP's 3.9.2 release (Issue https://github.com/lx865712528/ACL2019-ODEE/issues/5);
• In the Jupyter Notebook, calinski_harabaz_score should be changed into calinski_harabasz_score