setRatePolicy based on effectiveId. Fixes #110

Previously when getType() was defined for a type of object, shiny.js would
send updates immediately instead of applying the rate policy.
Bump version to 0.4.0
Bump version to 0.4.0.99 for development
reactivePlot: correctly pass width and height to renderPlot
Update NEWS
reactivePlot: fix infinite recursion when height/width is function
Bump version to 0.4.1
Add shiny metadata channel and send pixel ratio

This adds support for retina-resolution displays
Partial change to reactiveValues
Add manageInputs() to handle metadata and normal inputs
Rename .metadata to clientData
Rename  to
Move .shinyout_xx to .shinyclientdata_output_xx