Allow wildcard search on the sender (contact) for messages

Summary: Allow searching for messages by contact

Test Plan: Login on Workspace, click "All Messages" and on search type an email e.g ''somejunkemail@vs.ushahidi.com

Reviewers: eyedol, dkobia

Reviewed By: dkobia

Subscribers: shadowhand, rjmackay, srutto

Maniphest Tasks: T240

Differential Revision: https://phabricator.ushahidi.com/D199