v.2.1.0: Merge pull request #27 from netpieio/dev

• simplify netpie microgear datasource settings
• add slider widget
• add feed datasource
• add feedview widget
• add theme switcher

netpie-freeboard

• Add a toggle widget.

netpie-freeboard

• First release with NETPIE microgear datasource.
• Include a button widget.