Add "send custom message" to manage workers page

[IanEisenberg]

Add a button to send a message to a worker via boto's notify_workers command on this page:

@rwblair

[IanEisenberg]

Contact worker button works great. It would be helpful to have a larger message box, or one that expanded if the message extended beyond the space.

[rwblair]

Alright updated it to use a bigger text area by default.