Column.describe should work on string columns

[mikusp]

Calling describe on a string Column will error because of missing min on strings

[mwu-tow]

Likely to be solved together with #59, #70 and #72, What is the output you'd expect in such situation?

[sylwiabr]

I would say: count, unique, top and freq. Moreover Date column should have describe as well with: count, unique, top, freq, first, last

[sylwiabr]

Closing this one in favor of https://github.com/luna/Dataframes/issues/96