Image effect can consume memory and CPU

This issue was created to cover the following items that were NOT ADDRESSED as part of https://jira.atlassian.com/browse/CONF-29266:

1. If the gaussian blur we're applying is always the same (image shadows), we should do one of two things:
   1. Store and display the shadow as a 9 grid (check the image in https://code.google.com/p/scale9grid/) and use that, either when processing the image on the background, or maybe even when displaying on the client itself, although that will be more difficult to do.
   2. If shadows are not always rectangles, we can use box blurring instead of gaussian. Its faster to process and uses less memory.
2. Also, we can process only the border we need to process the image, instead of the whole image size.