Send Email to Contact - Integrate with History; Support for Single Contact Send

Extend the existing 'Send Email to Contacts' task functionality and integrate with Activity History.

1. Add a To: field (frozen in 'batch task' mode) to the Form/Task/Email which lists the name+email of all recipients in a simple comma separated list.

EXAMPLE
To: "Dave Greenberg" <dggreenberg@gmail.com>, "Donald Lobo" <lobo@yahoo.com>, "Jane Bar"
<jane@foobar.org>

2. Implement Task/Email for sending to a single contact:
2.1 This will be linked from contact/view/activity tab: "Send Email" (place link above Activity History selector).
2.2 Clicking this link brings up Task/Email form.
2.3 In this mode, check if contact has multiple email addresses. If only one email, we render To: field in frozen mode (as in batch mode above). If multiple, the To: field is rendered as a drop-down with all available email address options. The preferred address for the primary location is selected. Option labels include email address, location_type label and preference indicator.

EXAMPLE:
<option value="dgreenberg@gmail.com" selected>"David Greenberg" <dggreenberg@gmail.com> Work (preferred)</option>
<option value="dave@northtower.com">"David Greenberg" <dave@northtower.com> Work</option>

3. Integrate w/ Activity History:
The current code is already inserting a crm_activity_history record with callback = showEmailDetails and activity_id keyed to record it inserts in crm_email_history.
3.1 Implement logic for the callback - should forward to url which displays send date, subject and message (new page/template needed for this).