Bug 14266: Replace trim() with $.trim() in opac-shareshelf.tt

Bug 14266: Replace trim() with $.trim() in opac-shareshelf.tt

This patch replaces trim() with $.trim() which is supported
in versions of IE older than IE9.

Revised test plan
=================

Before applying patch:

0) Use IE 8 or Document Mode 8 in a newer IE using F12 Developer Tools
1) Set OpacAllowSharingPrivateLists to "Allow" in Global System Preferences
2) Create a private list in the OPAC
3) Add a record to the private list
4) Click "Share" or "Share list" on one of the list screens
5) Type in an email address and click "Send"
6) Note the error in the console log
7) The page should submit

Apply the patch:

7) Hold shift + refresh the browser to update any Javascript cache
8) Try to "Share" the list again
9) Note that the form submit after clicking "Send" and
that there are no errors in the console log

http://bugs.koha-community.org/show_bug.cgi?id=14266

Signed-off-by: Indranil Das Gupta <indradg@gmail.com>
Remarks: Works as per revised test plan
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>