v0.2.8

Transformers v0.2.8

Diff since v0.2.7

Merged pull requests:

• Fix typo in README.md (#150) (@LilithHafner)
• Fix warnings in tests regarding \eps (#152) (@originalsouth)

Closed issues:

• The text generation example outputs an error related to print_tree() (#145)
• Masks are broken. (#146)
• Gpt2 tokenizer does not support different vocab_size (#148)