BUG: GH3611 fix again, float na_values were not stringified correctly

     now, 999.0 (a float) will have: ['999','999.0'] added for matching
BUG: add na_fvalues to parsers to enable matching of float values w/o relying on string matching

     for an exact match
ENH: pull pandasjson back into pandas
DOC: add ultrajson license
TST: json manip test script. and trigger travis
BLD: fix setup.py to work on current pandas
CLN: revised json support to use the to_json/read_json in pandas.io.json

DOC: docs in io.rst/whatsnew/release notes/api

TST: cleaned up cruft in test_series/test_frame
DOC: io.rst doc updates
API: to_json now writes to a file by default (if None is provided it will return a StringIO object)
     read_json will read from a string-like or filebuf or url (consistent with other parsers)
ENH: removed json argument, now path_or_buf can be a path,buffer,url,or JSON string

     added keywords parse_dates,keep_default_dates to allow for date parsing in columns
     of a Frame (default is False, not to parse dates)
ENH: added date_format parm to to_josn to allow epoch or iso formats (which both can be

     can be parsed with parse_dates=True in read_json)
BUG: patch in weird nested decoding issue, courtesy of @Komnomnomnom
Merge pull request #3841 from jreback/GH3611_2

BUG: GH3611 fix again, float na_values were not stringified correctly
DOC: cooking.rst update
Merge pull request #3804 from jreback/ujson

ENH: add ujson support in pandas.io.json
TST: Fix missing import in io/tests/test_json …

Nose import is missing. If you get to the error at the last line (under
urllib), python complains because nose is never imported.
Merge pull request #3855 from jtratner/patch-1

TST: Fix missing import in io/tests/test_json
TST slicing regression test
Merge pull request #3858 from hayd/TSTassign_subset

TST slicing regression test
ENH: add toplevel eval function

This also adds a new directory in the top level pandas directory, called
"computation". Further development on out-of-core processing should be placed
in this directory.