Add support for Copy/Paste operations for Image element

Add support for Copy/Paste operations for Image element

Although Clipboard operations for text and markups work well,
when image is long-pressed, copied (Copy Image) and pasted - nothing
happens.

This patch introduces copy/paste support of images. This allows
for pasting images to richly editable field and text fields
(URL otherwise).

This patch is a tizen_src part of the implementation (Webkit is here
http://165.213.202.130/gerrit/#/c/95868/), which uses image markup to
generate all necessary clipboard data.

You can check it by selecting "copy image" on html5 "badge" image
and then pasting it into editable area on the following adress:
http://html5demos.com/contenteditable

Original author: Lukasz Bialek <l.bialek@samsung.com>
Based on patch: http://165.213.202.130/gerrit/#/c/92243/

Bug: http://web.sec.samsung.net/bugzilla/show_bug.cgi?id=14453

Together with: I11136d8352014f1acca144a0c4416c3bcf432e0c

Reviewed by: a1.gomes, djmix.kim, g.czajkowski

Change-Id: I11126d8352044f1acca044a0c4416e3bcf412e0c
Signed-off-by: Pawel Forysiuk <p.forysiuk@samsung.com>