Update tabipy.py

Fixed typo and cleaned doc string.
Fixed Typos, modifieddoc strings to be consistant with PEP 257, and fixed the implementation to include adding TableCells with col_span>1 at time of creation by adding cells containing '' in the spanned areas.
Merge branch 'col_span' into cell_method

Conflicts:
	tabipy.py
Added upades from col_span changes
Merge branch 'cell_method' into row_span

Conflicts:
	tabipy.py