Merge pull request datacamp#396 from datacamp/feat/update_has_expr_fe…

…edback

[LO-1231] Feat/update_has_expr_feedback

Updated shorten_string logic

Updated 'Expected something different' message logic

Added logic for shortening long outputs and added tests

Added has_newline and shorten_string()

Fixed string-shortening in format_string()

Fixed string-shortening in format_string()

Added string formatting for newlines and long strings

Merge pull request datacamp#395 from datacamp/fix/has_expr_string_for…

…matting

[LO-827] Fix/has-expr-string-formatting

Fixed comments for clarity