Fix and test height issues

[chriddyp]

• Handles filtering panel height
• Handles arbitrary row heights
• New property: max_rows_in_viewport which takes precedence over min_height. Viewport will shrink if there are less rows than max_rows_in_viewport supplied, otherwise it will display all max_rows_in_viewport rows
• Integration screenshot tests for all of the permutations of the row_height, min_height, rows, filterable, and max_rows_in_viewport

[chriddyp]

Fixes https://github.com/plotly/dash-table-experiments/issues/38

[chriddyp]

To summarize the height behaviour:

• By default, up to 10 rows are displayed. If only 5 rows are supplied, only 5 rows will be displayed and the viewport will shrink. If 15 rows are supplied, 10 rows are displayed.
• If max_rows_in_viewport is supplied, up to max_rows_in_viewport will be displayed. This is 10 by default. So, if max_rows_in_viewport is 20 and 5 rows are supplied, only 5 rows will be displayed and the viewport will shrink. If 25 rows are supplied, only 20 rows will be displayed.
• If min_height is supplied, the viewport will be resized to min_height regardless of the number of rows that are supplied.
• If max_rows_in_viewport is supplied and min_height is supplied, max_rows_in_viewport takes precedence.