1. DataFrame.renameColumn

2. DataFrame.show() and _repr_

3. Use simpleString() rather than jsonValue in DataFrame.dtypes

4. createDataFrame from local Python data, including pandas.DataFrame

Author: Davies Liu <davies@databricks.com>

Closes #4528 from davies/df3 and squashes the following commits:

014acea [Davies Liu] fix typo
6ba526e [Davies Liu] fix tests
46f5f95 [Davies Liu] address comments
6cbc154 [Davies Liu] dataframe.show() and improve dtypes
6f94f25 [Davies Liu] create DataFrame from local Python data