Create expandable comment boxes

[ananyo2012]

This is an added functionality over the comment box that will be used for posting comments. Comments boxes should be compact preferably one row and expand when content spans across multiple lines. This should be done as scrollbars for overflowing content makes it difficult for the user to read the input, for small textareas. Expandable text areas are the best solution for this. You can take help from this article http://alistapart.com/article/expanding-text-areas-made-elegant.

[ananyo2012]

Blocked by #62 and #61