added jsontags.py as a helper to serialize objects in json
converted sequential.py from yaml tags to json tags, cf https://github.com/nltk/nltk/issues/540
removed pyyaml install instructions from install.rst as it's no longer required by nltk
removed the yaml requirement from pip-req.txt as it's no longer required by nltk
added unit tests for nltk.jsontags
Merge pull request #557 from jskda/pull_request.json_tags

Pull request.json tags, cf https://github.com/nltk/nltk/issues/540
fixed stanford tagger tuple bug in python 3
use sre to process regexes properly to remove capturing groups
allow multiple class paths for java in nltk.internals, fixed some small bugs
decode stderr in the error message for nltk.internals.java
added interface to stanford parser, c.f. https://github.com/nltk/nltk/issues/522
added batch_parse()
implementation for tagged_batch_parse()
delete file after using NamedTemporaryFile(), added comments about windows' incompatibility without using delete=False
Wordnet common hypernyms lookup speedup and refactoring
Wordnet common hypernyms lookup speedup and refactoring
Wordnet common hypernyms lookup speedup and refactoring
Merge pull request #560 from jskda/pull_request.stanford_parser

Interface to stanford parser, cf https://github.com/nltk/nltk/issues/522
Update internals.py

It might be a good idea to make the distinction between capturing and non-capturing groups since technically, they are all grouping parentheses. I've only changed the docstring for this function slightly but maybe the function name shld be updated accordingly if others have this confusion in the future.
added "Author" headers