Bug 1253 Updating the VNFD via ngUI breaks charms execution

 * Fixed the bug by adding the symbolic link while extracting
   the file and while doing tar.
 * The file upload size is increased upto 50MB in UI

Change-Id: Ib1de6129018f11ce863a12a60e2ffab04187e795
Signed-off-by: Barath Kumar R <barath.r@tataelxsi.co.in>