Add Total Page Weight Metrics to the mobster report

[hariramachandra]

What : We need to provide the total page weight metrics in the Mobster performance report as part of the Page Metrics table

Why : It would be useful for developers to measure the total bytes download (a.k.a. page weight ) for each page. This will help them to understand the potential implication of their feature enhancements on the performance of their pages

How : We already have the size of each component in a page under waterfall . We need to add a functionality in the visualization/reporting module to summarize the size of all the components downloaded in a page to represent the total page weight.

[hariramachandra]

This is duplicate of #11