Make json data expandable and collapsed by default
Slim down data column to save vertical space
Reduce vertical space in table
Set error tag color to red permanently

Other tags take their color from an array that's cycled through as new
tags are added to the page, meaning that they will be different colors in
different instances of tv.
Adjust data arrow icon for expanded data rows
Adjust spacing and width of table columns
Add millisecond data to timestamps
Add basic nested JSON expand/collapse functionality
Fix collapse/expand JSON display bugs
Add basic row grouping functionality
Make group rows checkbox typography match other labels
Remove basic grouping behavior functionality

We're going to rework the grouping behavior and get it done the right
way.
Merge pull request #48 from alexlande/master

Design adjustments, json view improvements, basic grouping styles