index is included in memory usage by default
...and sys.getsizeof returns correct value. Closes https://github.com/pydata/pandas/issues/11597

Is this the best implementation for a common method across classes?

@jreback Python 2.6 error with `delta` argument on `assertAlmostEqual` - should I skip the test on 2.6 or find an alternate way of doing this?

xref https://github.com/pydata/pandas/issues/7718
 @jreback `assertLess` isn't supported either on 2.6? 
But we're green
 @jreback updated & green
 @jreback updated & green
 @MaximilianR lgtm.

can you run: `git diff master | flake8 --diff` and fix those issues. we are going to be shortly enforcing this, so might as well not add to it :)

ping when green.
 Done (phew...)
 lgtm. ping when green.
 merged via https://github.com/pydata/pandas/commit/60cacabdd37dcfb00920aed453787e77358219d1

thanks!
