ENH: add to_frame method to Series
Adding a method to Series to promote it to a DataFrame.  I've wished this existed so that when a method returns a series, and you could easily promote it to a DataFrame so that it's easier to add columns to it.  

pls also add a release notes entry (you can reference this PR for the issue number), enhancements section.

also add to the docs section in api.

and a 1-liner in v0.13.0.txt
 pls change the name of the method to `to_frame`....for consistency with others ,e .g.`to_panel`....
 See updated commit.  Thanks for all the feedback. 

@jreback let me know if the tests don't address the case you're concerned about
 "also add to the docs section in api." how do I do this?
 edit docs/source/api.rst

just like other files
 on another note, how do I generate the docs for testing?
 make doc
then view in a browser
 http://pandas.pydata.org/developers.html
 Updated commit should include docs update.
 can u add same line in v0.13 to doc/source/release.rst as well

@cpcloud @jtratner comments?
 just needs the name changed to `to_frame` then good 2 go
 @drasch thanks!
 doh, I just added the release.rst entry
 no worries I added on the merge 
