DOC: Update ecosystem.rst: Add IDE, IPython, qgrid, Spyder, API, quandl, Out-of-core, Blaze
I added a 'Graphical User Interfaces' heading.
- https://bitbucket.org/spyder-ide/spyderlib/pull-request/31/implementation-of-pandas-dataframe-issue/diff
- TODO: Add https://github.com/quantopian/qgrid
 https://github.com/quandl/Python also pulls data into DataFrames. Maybe an (data) API section?
 Done.
- GUI -> IDE
- IPython > qgrid
- APIs > quandl
 Should be ready for review
 Should be ready for review (pending build completion) ... `rst2html.py ecosystem.py` seems to work okay.
 Moved IPython into IDE section and added a blurb per https://github.com/pydata/pandas/pull/8507#discussion_r18586499
 ... Don't know where to put Blaze: http://blaze.pydata.org/docs/latest/backends.html#backends
 maybe make a new out-of-core section ..

fyi would move Vincent to the end of that section
 lmk when pushed
 Pushed.

May need to merge under https://github.com/pydata/pandas/blob/master/doc/source/ecosystem.rst#xray
 rebase to master and repush pls
 rebased and pushed
 thanks!

pls review the built docs (once Travis is finished with them)
 Thanks! Will do

https://pandas-docs.github.io/pandas-docs-travis/

https://pandas-docs.github.io/pandas-docs-travis/ecosystem.html
