add encoding parameter to add_keyword_from_file()

[liacoponi]

It would be useful to specify the encoding of the file in the add_keywords_from_file. Passing **kwargs seem an overkill since no other parameter is useful for parsing the file.

[coveralls]

Coverage remained the same at 99.298% when pulling 0d9a296 on liacoponi:patch-1 into 1c970b5 on vi3k6i5:master.

[coveralls]

Coverage remained the same at 99.298% when pulling 0d9a296 on liacoponi:patch-1 into 1c970b5 on vi3k6i5:master.

[vi3k6i5]

Travis CI build was failing because code changes were not compatible with python 2.6, hence changed the approach for getting encoding parameter using

with io.open(keyword_file, encoding=encoding) as f:

Instead of jsut open(

Still thanks for the pull request 👍