BUG: Fix wrong str.format() calls in Index.summary

GH3869
Merge pull request #4751 from jtratner/fix-summary-GH3869

BUG: Fix wrong str.format() calls in Index.summary
BUG: Fix crash using to_csv with QUOTE_NONE

Now passes `quotechar` to csv's writer. Default is same as csv (`'"'`),
but sets to `None` with `quoting=csv.QUOTE_NONE`.