getPCPList on new Contribution does not filter

To reproduce:
1) Create a new contribution.
2) Create >10 PCP pages
3) Try to allocate the contribution to a PCP page which is not in the first 10 created.

With >10 PCP pages in the system, you will only ever see the first 10 and it will not filter PCP's based on user input.

JSON from client side is:

Array
(
[className] => CRM_Contact_Page_AJAX
[fnName] => getPCPList
[json] => 1
[context] => contact
[reset] => 1
[term] => Campbell
[_] => 1420990743660
[q] => civicrm/ajax/rest
)

The request from client side uses the label term and on server side the variable read (instead of term) is 's' which is empty - the empty query returns first 10 records in civicrm_pcp rather than erroring out so fails silently.

See: CRM/Contact/Page/AJAX.php - function getPCPList()

PR to follow.