Added dropna to docstring for HDFStore.put()
HDFStore.put() method accepts dropna boolean parameter as it is passed
directly to the internal _write_to_group() method, but it was not
explicitly documented (as it is for append).  Also settable via option.
Just added 2 lines to the put() method docstring to mention it explicitly - copied from append()

great.....can you squash to 1 commit: https://github.com/pydata/pandas/wiki/Using-Git
otherwise looks fine
 you didn't need to close the other and open a new one

you can simply force push which overwrites the commits (this is what squashing then pushing with `-f` will do, FYI)
 @davidljung did you close this?
 @jreback - yes - I didn't realize.  I'll try to get it right when I have another moment.  Obviously, fairly new to GitHub and my attempt to squash from your link doesn't appear to have worked.  I'll figure it out. (Sorry for so much trouble for a 2-line change - but I'll know for next time)
 hah!

git-fu is tricky at first.....that's why its nice to figure it out on a smallish change!

you can reopen one of these and just force push to it
 gr8 thanks!
