This is a solution for lambda function feature request in #23
Created out_of_vocabulary_handler
Added ability to handle lambda function
the lambda function gets token_og_case, which has the original casing
I realized that the current release is implicitly using .lower() if an invalid option for out_of_vocabulary_token_option is passed (eg: out_of_vocabulary_token_option = 'upper')
This is a solution for lambda function feature request in #23
out_of_vocabulary_handler
.lower()
if an invalid option forout_of_vocabulary_token_option
is passed (eg:out_of_vocabulary_token_option = 'upper'
).title()