Log Message:
V 1.7.0
Remove DateY and replace it by real XY datetime, date, time and timedelta \ 
support. (#188)
Introduce new XY configuration options: `xrange`, `x_value_formatter`.
Add show_x_labels option to remove them and the x axis.
Set print_values to False by default.
Fix secondary serie text values when None in data. (#192)

V 1.6.2
Add margin_top, margin_right, margin_bottom, margin_left options which defaults \ 
to margin. (thanks djt)
Update django mime parameter from mimetype to content_type. (thanks kswiat)
Allow a color and a style parameter to value metadata.

V 1.6.1
Fix Decimal incompatibility

V 1.6.0
Adds config option missing_value_fill_truncation. (thanks sirlark)
Avoid HTTP 301 Moved Permanently (thanks jean)
Add a Django response method (thanks inlanger)
Fix setup.py (#170)
Fix format error on list like in table
Add legend_at_bottom_columns option to specify number of columns in legend when \ 
at bottom. (#157)
Fix secondary interpolation (#165)
Adds an extra class (axis) to horizontal guides if the label is "0" \ 
(#147) (thanks sirlark)
Add line stroke customization parameters to style.py (#154) (thanks blakev)