Get Phabricator projects for paste events

Summary:
Phabricator uses a new generation search endpoints for modern API calls.

See https://secure.phabricator.com/conduit/method/paste.search/

We use this new endpoint to get projects in attachment for paste events.

Test Plan:
Send again a paste notification request through Runscope

15:13:48 < Wearg> FRWPKumkum created P147 Ressources cartographie théorique.

Reviewers: dereckson

Differential Revision: http://devcentral.nasqueron.org/D129