Add auto play and size config to carousel widget

Closes #588, #633 

Defaults - 
* auto play = true
* auto play interval = 5 seconds
* size (max height) = 'Medium' 

Size options' values - 
* Small = 200px
* Medium = 350px
* Large = 350px

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![spotlight-issue-633](https://cloud.githubusercontent.com/assets/302258/3170229/5d399c3e-ebb3-11e3-8b2c-72bec9e25ff2.jpg)