Bug 26350: Librarians can request discharge on behalf of patron

Bug 26350: Librarians can request discharge on behalf of patron

While deploying discharges in our library we figured out that librarians
need ability to request discharge document on behalf of patrons from
intranet page.

It was logical to add another option on Discharge patron tab.

It nicely addresses Bug 16466 since it shows status of pending
discharge instead of button to issue new discharge.

To test:
1. apply patch
2. make sure that useDischarge is enabled in administration
3. verify that "Request new discharge" button is availabe, click on it
4. after page reload, message "Patron has pending discharge request."
   will appear
5. click on "Generate discharge" to approve discharge and generate
   pdf (this is unchanged compared to exsting workflow)